ive got an 84 trans am ive converted to an 88 gta, it has the stock gta wheels and the 84 7.5 26 spline rear. how much stronger would a 99 t/a rear be? i found a good deal on one with 4.11 gears but am concerned it will make my gta wheels stick out to far...has anyone done this? should i get it? there is something wrong with my current rear, did a burn out the other day and heard a pop, now it makes alot of noise going around corners, havent driven it since, it has a powertrax locker in it also. ill pull the cover off tomorrow and inspect.

 

Not too much stronger since the ring and pinion are roughly the same size however the axles are quite a bit stronger and instead of 26 spline axles the newer rear has 28 spline axles..
you will need to run 4th gen back space rims.

 

they are roughly the same strength as any late model third Gen.. You can find a 91/92 axle that is just as strong as a 4th Gen. axle. The 4th Gen. axle is roughly 4" wider (two on each side), bolts directly in, but you will need roughly 2" spacers if you want to run the GTA wheels, as they will hit the calipers. Otherwise, if you were to get the 4th Gen. rear, and you wanted to maintain your stock width, you can go through all the labor of getting the axle you want, swap the carrier into your axle, buy two new 28 spline axles for a 3rd Gen., and install the LS1 rear brakes onto your axle and you would have an equivalent strength axle to a 4th Gen. with the correct width, although you may need to still use spacers to fit the cross-lace wheels.

 

it might be a driver side axle, so how about upgrading to mosler axles? that with the powertrax should be stronger than a 4th gen rear right? im running an 02 ls1 and a t56