Or you could just stick a 3 speed auto trans in it and keep your 5.125's and run 32's.
Why would this help? No matter whether he currently has the 4 speed auto or the 5 speed manual, he could just run them either with the OD locked out (3rd in a 4 speed is a 1:1 ratio, just like 3rd in the 3 speed auto), or in 4th gear (4th in the 5 speed is a 1:1 ratio).
If for example he has a 5 speed manual now, he has the 5.125 axles correct? With my 3 speed auto, I swapped in a set of the 5.125 to replace my standard 4.30's and it was plenty of final drive reduction to pull 32's, before the turbo. Still not fast or paticularly powerful, b ut hey , these things stock are more economical than powerful. I think the auto transmission with it's torque converter just pulls better with less stress on other components.
Yeah, he has a 95 4 door, so it will have 5.12 gears, no matter what tranny he has.
Again, I can't see how swapping in a 3 speed auto will make it drive/pull any better than with whatever tranny he has now. Yes, starting out from a dead stop with a manual might be kinda doggy, but once he is rolling, it shouldn't be that big of a deal, and doesn't warrant a 3 speed tranny swap, IMO.
Yes, he could go to 5.38 or 5.62 gears, but that won't be as big of a jump as you when you went from 4.30s to 5.12s (which is what really saved you when you went to 32s with a stock 1.6, IMO....not the auto tranny).