4th gen rear vs 3rd gen rear
 

whats the diff between the to that makes people install the 4th gen rears in thirdgens ? are the 4th gen rears better in some way or another ??

4th gen rears are 2" wider on both sides (4" total). They also came with better gears usually and a Torsen lsd/posi. By using a 4th gen you can run 4th gen wheels which would otherwise require 2-2.5" spacers. The 4th gens also came with disc brakes which is nice if you're into the whole negative horsepower thing ;) .

negative horsepower thing??? so pretty much its just the cheapest way to get a posi slightly better gears and a disc brake conversion all in one ? what would you guys pay for a posi rear with 3.42 gears from a 95 z28 with 80k miles on it ? also would it be worth geting the rear if i plan on getting 3.73 gears instead of using the stock 4th gen gears ?

I sold my 94 rear axle assembly, 3.42 posi, for $300. Had about 50K miles on it. No calipers or rotors, since I reused those with the 12-bolt.

The dimensioned drawings on the Strange website show the 3rd Gen rear axle assembly to be 3" narrower overall, or 1.5" on each side.

for 4th gen parts you can't go wrong with www.contemporarycorvette.com
give them a call and tell them what you are looking for, they will have it in stock and at a fair price. you can also check around on ebay, their seller name is fparts.

later
tim

They are a better rear end then the Third gen rear. They are a little wider, and if you reuse your old rims, they will stick out.
The rear disks are better then most of the 3rd gen stuff. The only good rear braks for a third gen are the PBR set up after 89, and most people wont spare theres. 4th gens tend to have less milage on them, but becareful of how many launches they took, you know dem crazy LS1 owners and there engines made by God.

Actually for drag racing a thirdgen would be more ideal since the axles are shorter. It isn't a huge difference but the shorter the axles the stronger they are and less likely to twist.
Also like Big Als just said, the LS1 guys beat the crap out of their rears, so be careful what you get. I'm partial to my 3rd gen aluminum drum torsen (yes same as in 4th gens) richmond 3.73 rear :) . It's got almost 190k miles, the shafts are original, the rest of the rotating parts have been replaced when I did the torsen and gears.
If I were go buy now I'd get a 4th gen rear, that way when I upgrade to 17" wheels I have a larger selection and only need to buy the 2.25" spacers for the front.

yea i just rebuilt a PBR 9 bolt with new 3.73 gears and new differential...and now im buying the car the rear went into...pretty funny how that works...lol