Thinking about swapping the rear end from my 84 z/28 to a rear from an 2000 SS, I know the rear is wider but is it possible to use my stock 3rd gen wheels( will it stick out to far) or what back spacing would I need for wheels?

 

Yes, you can use the stock wheels. Yes, they will stick out about an inch or so.

 

I recently did that swap. They do stick out just a bit past the fender lips. I have my stock wheels currently. I lowered it at the same time. It doesn't look as bad as I thought it might, but I will change wheels eventually.
You can use 4th gen wheels or C5 Corvette wheels, but then you will need spacers in the front.

 

Stock Wheels with 4th gen rear



Stock Wheels with 4th gen rear

 

Is the 4th gen rear a direct bolt in, or are modifications required (other than wheel backspacing?

 

The rear end itself bolts right in. Coil springs, shocks, panhard bar, control arms, torque arm connect exactly the same on both rear ends. I even used the sway bar from the 4th gen.

There are some auxiliary things that have to be dealt with though. I went from 3rd gen drums to the lt1 pbr discs. I had to get conversion parking brake cables to replace the back left and right cables. I also had to get a new hardline from the rear junction block to caliper flex lines. The 4th gen rear I used was missing that line. If your 3rd gen already has disks you may be able to use your stock line, I'm not positive. I got all that stuff from Hawks and it worked perfect.

After taking apart my rear suspension and seeing how shot all the bushings were, how blown out the shocks were and how flimsy the factory stuff was I had/chose to do some upgrading. You could be in the same boat. I replaced all the away bar bushings, trimmed a bit off the coils to drop her a bit, installed Founders adjustable control arms and panhard bar.

 

Does the car handle any differently with the 4th gen rear and the slightly wider rear tire spacing? How about when pressed to the limits?

 

It definitely is more prone to oversteer now. I went up one size larger in in rear sway bar size, though, and made some other upgrades as well, so I can't be sure of the cause. It isn't really an issue unless you are heavy on the throttle while turning. Part of it may be because I know have a limited slip diff, whereas before when it was open I would just spin the outside tire and would never get much traction. When I upgrade my wheels and tired I'll get some the bring the wheels back in so we will see if that changes anything at all.

 

The axle HUB on all 98-02 "LS1" rear-ends is a little larger than Thirdgen or "LT1" axle hubs,... so you might need to shave a little from your factory wheels center hub-hole to get stock 82-97 wheels to fit on the axle properly.