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Hello gentleman. This is my first post and I could use some help/advice. My truck has a 400 with a three speed (plus granny) transmission. The seal went between the transfer case and the tranny so the tranny fluid runs into the transfer case. Do I replace the seal or bite the bullet and switch to an auto trans? If I go auto: 1) What tranny will bolt up to a 1979 400? 2) What should I switch the ring and pinion to so I can get more speed out of this girl? (currently 50 mph and she is screaming) 3) Do I need a donor truck or can I work it out with the brackets, etc. needed for the swap? Im not sure of the gears in the truck. Would the auto tranny be enough to gain some additional speed? Thanks for the help.
 

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Replace the seal.

In order to swap properly to an automatic you'll need the automatic column, the pedal assembly, transmission (C6 4x4 transmssion, by the way), and both driveshafts are different lengths. Possible the crossmember is different, but not 100% sure on that.

Oh! Also the wiring down to the neutral safety switch. Probably forgetting something.

C6 auto and your 4-speed tranny all have the same top gear ratio so that won't affect your highway speed.

What size tires are you running and how many rpm is it running at 50 mph?
 

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like mentioned,much easier to repair what you have,unless you are tired of shifting gears

you must have some steep gears or really small tires to be screaming at 50 mph

the t case is not stuck in 4 low is it?
with my 78 auto bronco,at 50 mph in low range I can run around 50 at over 5000rpm
in high range, at 85 I am around 3500 rpm

and if swapping to auto from stick,pedals could be left in,just remove clutch pedal
 

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I have done the auto to manual swap on a few trucks and back the other way on a ranger I can tell you from experience its always easier to go from manual to auto with a non computer controlled trans anyways. really the only problem you would have is rigging up a shifter and the kick down stuff if you just get the trans.

best thing to do is find a donor truck with a blown engine if you can. take what you need/want and sell the rest. I have done this a few time and it usually pays for the swap just takes for ever to sell everything that's worth anything sometimes and the worst part is you will have a truck strung all over hell while you are tearing it apart.

also don't get a 2wd c6 and think you will just convert it to 4wd you have to dismantle the entire trans and its not worth it.
 

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Discussion Starter #5
Thanks

After sleeping on it I think I will stay with the current configuration. Too much additional money to put in. Besides the leak everything else seams fine. Kind of like jumping out of a perfectly good airplane I guess. So that leads me with the speed issue. I have 33 in BF's. I am not sure of the rpm's at 50 but its definitely up there. Not sure of the rears either nor have I ever changed a ring and pinion.
 

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They call me "MR FLAT TIRE"
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sounds like an interesting rig....can you post a photo or two? its ok to brag a bit about your ride :thumbup
 

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those old 4 speeds just weren't made for speed they were made for torque I put one in my 79 bronco and it wasn't gas friendly on the highway at all but it sure did pull a lot better for trails then the c6 did in my opinion.
 
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