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Discussion Starter #1 (Edited)

This is my experience with swapping a C-6 for an AOD. I suppose it could also be used in reverse to aid in an AOD to C-6 swap. It is not intended to provide technical (rebuild/upgrade) information nor debate on the worthiness of the AOD or C-6. I may also buy /install something new that others prefer to fabricate.

This write up is divided into 5 sections.

1) Part 1 intro
2) Part 2 - Parts and part numbers (where available) needed.
3) Part 3 - C-6 removal
4) Part 4 - Installation of the AOD
5) Part 5 - Optional equipment and adjustment.
6) Part 6 - Post install observations etc

If you find a mistake, let me know and I will correct it. There may be alternate opinions on what to do first, and I understand that. I didn’t take pics of every step along the way, I work alone, made notes on the fly, and I may have very well left out something. I assume anybody doing this will have some mechanical / Bronco experience. My main focus is to provide info on what I found necessary to do the swap, and any helpful hints.


My Bronco is basically a stock 1989 factory equipped with a 351 (5.8) EFI, C-6 with manual shift transfer case. It has stock size tires and no suspension nor body lift. The only options you might see are the exhaust i.e. Summit shorty headers and Bassani exhaust. My intention is to have a comfortable long-range cruiser. For this reason I chose the AOD. At 70 mph, with the C-6, the engine tached 2500 rpm.Gas mileage in town was 9 and highway was 12.

Also, I have done a frame off restoration (resto-mod) and many of the original Ford nuts and bolts may not have found their way back. If the sizes I give are different from yours, sorry, but they probably got substituted.

I sourced my rebuilt AOD from a seller on Ebay. He bought it from PATC for a project. It came with a torque converter.

Finally, this truck will probably not see a track nor trail while I own it, so I am not worried about bullet-proof.

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Discussion Starter #2 (Edited)
C-6 to AOD SWAP Part 2


1) Captain Obvious says……an AOD transmission from a 4wd application.
(You can start with a car trans but you will need to change the output shaft. Technically beyond the scope of this.)
Also, the level of “build” is beyond the scope of this thread.

2) AOD extension housing for 4wd. The old one from your C-6 will not work.

3) Torque Converter for an AOD.

4) Flexplate (sometimes referred to as a flywheel) for the 5.8 / AOD combination. This was available in the Ford Crown Vic and Mercury Grand Marquis. I don’t have the exact years, but my guess would be be mid 80’s to 1990 or 91.

FLEXPLATE: FORD part # E0AZ-6375A list $ 111.88 (I paid 83.91)

Motormite 04352
Hays 12040
NAPA BK 6005012
TCI 529628

4) TV cable and brackets from an AOD equipped truck or Bronco.
TV CABLE: Ford part # F2TZ-7F042-A (cable only) - obsolete from Ford.

5) Shifter Bell crank from an AOD equipped truck. SEE NOTE 5 BELOW.

6) Transfer case shift arm from a 5.0 / AOD equipped Bronco or truck.
(Ford says it’s a 1990 - 91 only, and I have one on order)
Part number to be provided in future. Absent that, the original arm could be lengthened.

6) AOD NSS pigtail (plug) - not absolutely necessary but it makes life easier to graft to the C-6 wiring.

7) Wire ends & connectors to transition between C-6 NSS and AOD NSS. Weatherpack recommended.

8) In case yours is missing. AOD dipstick tube: E5TZ-7A228-E List $45.93
Yes, it can be sourced from the recycler. Mine leaked, so I ordered a new one. Mine also seemed bent ‘cause it was a major PITA to install.


9) Re-bend/modify rear transmission cooler line- Flaring required.

10) Shorten / lengthen driveshafts .

NOTE: An AOD with extension housing is 1 1/8” (1.125”) longer than C-6 with extension. That would seem to dictate shortening the rear and lengthening (re-tube) the front. This is probably considered un-necessary by some. I prefer to err on the side of safety. In the event of a severe jolt, I don’t want to see stuff bottom out and break a transfer case or disconnect a shaft. A lifted or lowered truck obviously has different considerations. It cost me about $50 to shorten and rebalance the rear, and $400 to have a new front tube made. The slip shaft on my front was heavily worn. Price included rebalance.

Rear shaft - flange face to flange face 33-1/4"
Front shaft - u-joint center to u-joint center - 37"

REMEMBER, if you are harvesting from a junkyard, the AOD truck will have a 5.0 / 302

NOTE 4: My items 4 &5 came from Pick n Pull so I have no part number(s). Again, AOD cable is NOT available from Ford anyway. On the TV cable, you can disconnect it at the throttle body plate (slide forward and pull up), and take everything else connected to it. That includes the bracket at transmission bell housing, and the outer TV lever (arm) if it’s not on your trans. Mine wasn’t. You can not use a “C” shaped car application lever. The truck lever is straight.

NOTE 5: You will need to disconnect the column shifter arm from the column (remove the nut) and take everything else between that and the selector arm at the transmission. That includes the bell crank between the frame and the bell housing. Yes, the frame end bolts (2) are a PITA to get to and will probably be heavily rusted. The wire loom strap doesn’t help.

While the C-6 stuff looks similar and the cables are almost identical in appearance, they are different and don’t readily exchange.

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C-6 to AOD SWAP Part 3 Removal


Most of us have removed a transmission before, so this is not a perfect by-the-numbers instruction manual. Just some pics and helpful tips (hopefully) for along the way. It’s nice to know someone else has walked down the path and can provide a heads up on potential problems. I hate surprises.

1) Remove the skid plate.

2) Drain the transmission fluid (2 qts.) from the transfer case using a 3/8” drive ratchet.

3) Drain the transmission by dropping the pan OR I used a MityVac pneumatic operated evacuator. Saves time and mess and leaves the pan intact to use for jacking. Well worth the $93.

4) Mark your driveshafts. Mine are going to get rebalanced, but I still mark them.

5) Drop the front and rear shafts. Mine used 12 point 12mm head bolts on the rear shaft and ½ head u-bolts on the front.

6) Disconnect speedometer cable at the rear of the transfer case. Push in and pull up on the clip.

7) Disconnect the VSS connector.

8) Disconnect the transfer case shift arm at the pivot. I used a large screwdriver and pryed carefully.

9) Disconnect the NSS and the transfer case “sender”

10) Remove the 2 - 8mm head bolts attaching the transfer case shifter. No need to remove the shifter, or the boot. I just pushed it up and rested the shifter on the floor ledge.

11) Remove the 6 13mm head bolts attaching the transfer case to the extension housing.

12) Transfer case isn’t that heavy, but use whatever you think you need to remove it safely. I.E. a helper, a transmission jack etc. There will be a trace amount of transmission fluid when separated.

13) Remove the large bolts holding the transfer case shifter body to the extension housing. 1-1/8” and 13/16” heads on mine.

14) Remove transmission shifter bell crank at the bell housing and the frame. The bolts on the frame end are a PITA, especially on a rust belt vehicle. Go ahead and remove the kick down cable. These wont be used again.

15) Remove the 3 - 3/8” head bolts on the inspection cover and block plate.

16) Good time to remove the “y” pipe. I suppose it’s not mandatory, but it sure makes life easier.
- curse - if you forgot to use anti-seize the last time.

17) Remove the 4 - 9/16 nuts holding the torque converter to the flex plate. I used a remote starter button to slowly rotate the engine exposing the nuts.

18) Disconnect the battery and remove the starter

19) While you’re topside, remove the 2 7/32 head screws attaching the throttle body shroud where all the cables hide.

20) Disconnect the kick down cable by pulling forward on the arrow shaped plastic piece. Lift up after it unsnaps. Then squeeze the tabs on the kick down cable and release it from the bracket. Shove it down the intake to the transmission.

21) Since we’re here, disconnect the vacuum line to the modulator. Mine was connected on the vacuum distribution block on the upper firewall on the passenger side. DON’T FORGET TO PLUG THE VACUUM SOURCE!! You wont need it again and the engine will run funny after all your work.


22) Disconnect the vacuum line to the modulator and put it aside. Won’t be needing it again.

23) Disconnect the transmission cooler lines. The forward line can be re-used as-is. The rear line will need to be re-bent and re-flared if you plan on using the stock factory cooler. (I am using an aftermarket cooler mounted near the gas tank so all my lines and original cooler were removed)

24) Remove the air line to the cat if so equipped.

25) Remove the 6 - 5/8” transmission to engine bolts.

26) Remove the 2 stubby rear transmission mount to extension housing bolts. Loosen the transmission mount to cross member nuts.

27) Remove the full cross member bolts.

28) Loosen the side brackets (braces). No need to remove them, just loosen them enough to clear the main cross member.

29) Support the engine. I used a floor jack with a large block of wood.

30) Should be ready to go now. Safety first!! Use a transmission jack or adapted floor jack to gently and slightly lift the transmission. Probably a good idea to check/ adjust the engine support.

31) Slide back the transmission until the torque converter clears the flex plate and everything I clear between the engine and trans. Lower it to the ground.

32) Remove the 6 flex plate bolts and remove the flex plate.

Leave the block plate - it’s the same.

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C-6 to AOD SWAP PART 4 - Install


1) Install the 5.8 / AOD flex plate. Rotate it until the 6 bolt holes align. Use Teflon thread sealant and torque to 75-85 ft/lbs. ((Per Ford manual))

For the most part, the procedure is a reverse of the removal (surprise!!), but I will add a few comments.

Trippple check your torque converter on the front shafts.. Make sure it is in properly before you start the install. I spin mine a number of times in both directions, with rearward force, until I am certain it is correct. THEN:

Keep the transmission level or the rear lower to ensure the converter stays in place.

After I am sure it is in place, I rough in the torque converter studs. I put one at the 6:00 position . I rotate the engine to closely match. Since the starter is out, sometimes it is easiest to just match the converter to one of the studs.

2) To install the transmission, I used a pair of “alignment pins” that have served me very well in the past. They are nothing more than 7/16-14 thread 3-¼” long bolts with the head ground down to a taper and a slot filed in the end (so I can used a flat bladed screwdriver to remove them if necessary)

Once the transmission is in the air at the proper elevation (to match the engine height and angle), slide it forward.


Check the converter studs in their alignment with the flex plate bolt holes. Make sure you pick the correct ones.

Slide it forward slowly until the stud just peeks through the hole. Double check the alignment and shove her home. The pins I used really help with aligning the converter and trans to the engine. They also give the transmission a place to “land” before it goes in. I like the security on knowing it’s sitting on them. I used 2 floor jacks with special wood bases to lift mine.

3) Install trans to engine bolts. If you don’t have a dipstick installed, it’s a good time to do so now. Just like the C-6, one of the bolts holds the dipstick brace.

4) Crossmember is the same, but I think I had to flip the transmission mount around. If yours looks like my pic, it will fit. I leave the mount in the cross member as I slide it under the extension housing pad. It’s a lot easier to accommodate the stubby ones than to try to lift the engine and transmission high enough to clear the long studs on the rubber mount. Should be obvious, but who knows.

Crossmember should bolt up with NO modifications!!

Connect or re-connect all your linkages

Connect your switches and electrical connectors.

Again, this isn't all inclusive, but it should help get you there. If I have left out a step, and you think it should be included, lemme know and I wlll add/correct.

BTW, AOD and converter take 12.3 qts of trans fluid and the transfer case takes 2. I used Castrol Mercon V . Even with the trans cooler is was almost the same as stock.


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To be provided soon.....but for now.

1) I like overkill. I installed an optional transmission cooler with fan and built in thermostat. B&M Hi-Tek # 70298.


2) TV line pressure gauge for easier adjustment and monitoring.

3) NSS - AOD pigtail to C-6 old harness.

1) Cooler info.
Mounted the cooler between the rear floor supports in front of the fuel tank. I opted for this location for several reasons:
A) I wanted to get rid of the metal lines that always seemed to be in the way....and run right into the heat of the engine.
B) Rear location was easy and provided a "channel" of cooler air for the fan to draw.
C) Not a major consideration, but reduced noise and vibration.

You may pick a different cooler or different location, but if you mess with the original Ford cooler line fittings (on the passenger side:rofl:) please note:



I opted for the lightweight black braided hose. It is lighter than the stainless and doesn't prick your finger :rofl:.
I used 2 10' sections. If you look at the pics, the top line (pressure) has a blue tracer in it. The return line is solid black.
I used A/N fittings vs flare.

If you use AN fittings, (leave the Ford fittings...and you will need 2 adapters to thread into the stock brass line fittings. RUSSELL Part # 640330. Now you wont have to pull yours and haul them somewhere and have the snot-nose:toothless kid in a yellow and black shirt try to figure them out. ((JEGS)) :rofl:


In addition, I installed a TV line pressure gauge under the dash. It allowed me to more accurately adjust the pressure and monitor the activity.

ADJUSTMENT with a Gauge

This assumes you have already installed a gauge. On my first AOD, I installed the small pressure gauge right in the "TV" port on the passenger side of the box, just above the pan. That required the 0-100 gauge and about a 1.5" long brass pipe with a connector. (maybe I can find some pics).

Also assumes you can make or have made a special spacer. I used a .500 wooden dowel that I whittled down and slotted for the TV cable.
Spacer needs to be .272" EDIT - CORRECTED DIMENSION (((NOT .385)))


2) Adjust with trans at operating temp and in NEUTRAL (DON'T FORGET TO SET THE E_BRAKE OR CHOCK THE WHEELS)

3) At the TV cable, (throttle body end) pull the little plastic (off-white/yellow) connector forward (at the end of the cable) and insert the dowel with the slot over the cable between that and the nylon stop. Dont discconect it, just pull it forward enough to install the dowel.
4) At an idle,TV pressure should be close to 32psi.
5) If it is not, you will need to unlock the TV cable. (I will find a good pic or you can google AOD adjustment)
6) Lift the locking tab by lifting it up. Slide the rear of the cable in/out to accomplish this.
7) After it is correct, relock it by pressing the tab down.

((I will find pics and refine my description as this is a
CRTICAL adjustment on an AOD ))

Mine is right at 32 and it shifts great.

3) NSS - AOD to C-6 old harness.


a) Pigtail from a 4 or 5 pin AOD (my trans had none) from the j/y
b) Appropriate wet location terminal ends or Weatherpack connector.
......I used a round 5 pin Weatherpack, which are hard to find.
c) Cut the old C-6 NSS connector (harness end, not the switch). ((Leave 1-2" of wire at the old connector in-case someone needs one!! or you want to go back to the C-6 in the future))
d) match 'em up as described below.
e) test.

AOD NSS in general, and FYI: 4 & 5 post used.
In all cases: 2 for the starter circuit (continuity is "P" and "N")
.................2 for the reverse lights. (continuity in "R" only)
5th post is a computer ECM function and not needed here (I think).
If you are interested, it shows ground in "P" so the ECM will go into diagnostic mode.

NOTE: My AOD NSS had 5 posts ....but there are 4 post NSS out there, and so goes the pigtails.
I harvested 3 pigtails. 2 were 5 wire, and 1 was a 4 wire.
A 4 pin pigtail can be drilled in the 5th position and used on a 5 pin switch.

On my C-6, there were 6 wires from the NSS connector. As best I could match to Ford wiring schematic.


1) Red/blue...........start
2) Red/blue...........start
3) Purple..............rev light
4) Black/pink.........rev light
5) Red/white.........neutral (transfer case?)
6) Blk..................neutral (transfer case?)

1) Black/pink........rev light
2) Pink/orange......rev light
3) Red/blue..........start
4) Orange/white...start
5) Red/white........ECM

Needless to say, I matched the C-6 wires to the same color on the AOD NSS pgtail where appropriate


red/white.......... N/A
black................ N/A

A picture is worth a thousand words: NOTE: TV LEVER IS INCORRECT FOR TRUCK


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Discussion Starter #6 (Edited)

To be provided ....soon....:thumbup

Preliminarily, I am very pleased with the results. It shifts great and at good intervals. It stays out of OD until 45-50. Then the rpms drop to 1000 or so. If I were a purist, I would probably say the differential gears could be a little lower (higher in number) to add back a little of the power band.

Gas mileage has improved to 10.1 from around 9. That's mostly in town.

I am anxious to take a road trip and post my results.

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Discussion Starter #7 (Edited)
Hey J.R. what does your gas mileage on the highway looking like? Or have you not tested it. I have the same setup 351W C6. But getting 10 mpg. I have done so much in trying to get the MPG to improve but I think a AOD is my last draw, just want to know if it’s worth it. My rig is my DD and I drive 23 miles highway every day.
I still haven't hit the highway in it yet. It has helped the in-town about 1 mpg. I probably wont get to take a long drive for a week. I will post the results. I can tell you that it makes the truck a lot quieter (on the short bursts I have done) since the engine isn't running at 2500 rpm.

At this point, the ONLY change I might suggest is the use of the low ratio gear set from 4R70W. OD in it is 70% vs 66% with the AOD. Of course it is only a 100 difference at about 70. Going from 1650 (AOD) to 1750 (4R70W). Again, not really a big deal.

With stock gears/tires it's a little sluggish at take-off and probably out of the power curve cruising. Might be even better to change the differential gears, but since I just did that, I will satisfy myself with the stockers.

I have the low gearset in my other Bronco and I noticed a big change in first gear performance.

......4R70W ...............AOD

1st = 2.84 ............. 2.40
2nd = 1.55.............. 1.76
3rd = 1................... 1.0
4th = .70................. .66

I'll keep updating as needed.

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Discussion Starter #8
I did finally get to do a short 142 mile road trip. The in-town mileage has been 9-10. It got 14-15 on the road.
I know there is something else wrong causing poor mileage, but I was happy that it made a big jump on the road.
The AOD and the stock gears "load" it up a bit. It runs a little over 70 at 1500 rpm. Now i gotta fix the mileage.

Overall, I am very happy with the swap. It shifts perfectly and behaves well.
I bought it off Ebay and I believe it was a PATC Dominator Jr.

455 Posts
:thumbup Great writeup, JR.
I agree, gearing it lower would get it
back into the torque curve and improve
both mileage and performance.

I'm thinking it should run around 2100 rpm
@ 65-70...? Just a guess.

4 Posts
ok im doing something like wat u did. only i have a bronco with a 302 aod trans and i want use a 351 from the same yr...90. went to the parts store to get a flex plate price and they could not find any 351 aod combo from a crown or a marquie. but really just wondering how its working with the combo u using?

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Discussion Starter #12
For whatever reason, my subscription to my own thread was dropped. I wasn't ignoring, just didn't know.

Sorry Blue....it's been 1-1/2 years, do you still need any pics etc?

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Discussion Starter #13
ok im doing something like wat u did. only i have a bronco with a 302 aod trans and i want use a 351 from the same yr...90. went to the parts store to get a flex plate price and they could not find any 351 aod combo from a crown or a marquie. but really just wondering how its working with the combo u using?
Well there is, it's just older. If you use the numbers I provided in post #2, you should be able to source it.

Mine hasn't given me a moments problem or concern in almost 5 years...(since I installed it).

8 Posts
About what did this run you to do the conversion? I have a guy that Is looking to trade his 89 5.8l/c6 bronco for my 2000gt and I have a 150 round trip daily drive ATM. So an aod swap would definitely be in the works.

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