Join Date: May 2009
Location: Upstate SC
Bronco Info: 1990 F150, 5.8 w/GT40X heads, Lightning intake, E4OD, 33" tires, detroit locker rear & true trac fro
There is a thread on here detailing 3G alternator upgrades. Several actually. Used to be a vendor that serviced the forum that had top notch stuff and sold custom harness, cables, etc to complete the job too.
He is no longer around, so you will have to source all that stuff yourself. PA (as in Performance Alternator) has the wiring kit available in harness form for a reasonable price. They also offer upgraded 3G 130 amp alts that put out a minimum of 160 amps. You would still need to upgrade your charge cables.
On your 90 (mine too) you will need to remove some material from your original bracket. Not hard to do with a $50.00 ish dollar dremel. I used the same belt.
When searching you should easily find factory supplied alternator sources, such as certain Tauras, Mustang, etc. I think any 94-95 V8 and 94 up (to an extent) V6 should work. Regardless, the correct factory replacements will be available in your favorite parts houses and possible junkyards if you prefer. There are two versions of the 3G, a 95 amp and 130 amp. Do your research and you will be fine. They are readily distinguishable by the number of cooling holes where the pulley mounts.
As stated above, if you have a roller cam you will have to have a steel cam gear for your distributor. I just swapped the gear from my donor engine (I had it rebuilt) onto a donor distributor from my wiring harness donor. The 90 will have a distributor mount TFI and the newer ones have a fenderwell mount TFI. (My truck was originally 5.0/AOD so since I was upgrading to a 351/E4OD and needed harnesses as well as engine/transmissioin.)
I am not 100% sure of the bracketry differences between the model years but I agree with the above, just use your existing brackets. If the cam is the factory truck camshaft, your computer should run the engine just fine. If it is a "performance" grind you may run into issues with the SD computer.
You should also be made aware, if not already, that the factory intake will be a big restriction especially with the better heads.