I'll second that and then some! Changing out ring and pinions is not a job for even a good mechanic. It takes someone with the proper dial indicators, and experience in rearend setup.
As for a posi unit, it's also cheaper to change to a Power Trax Locker than convert to, or buy a posi. They are under $400, and will do the same job as well, or better. A little noise when turning tight as they release, but I've had one for years and no problems. I don't mind the clicking at low speed city hard turns.
I had a supposedly experienced rearend guy install a ring and pinion set 30 years ago, and after about 100 miles the gears went out. I tried to do it reading the manual, but ended up paying a good rearend guy to assist me.

 

If you have a stock 292 geared rear in your car lower gears will not work you will have to find a stock 3.08 or 3.42 rear to go with lower gears due to rear housing will not allow change to lower gears due to housing size. 3.42 is lowest stock gear ratio offered in your year model.You need to find a z28 or trans am to find rear you need.

 

Thanks. I think that the best approach is to just have it done as this seems that it is not a beginners project. I do have a 3.08 rear end. Any advice on where to get the parts and exactly what Ill need?

 

Before you buy anything, you should open the phone book and call around for pricing. You might find someone that can supply the gears and install them as a package deal for a better price. Or you might ask what they charge if you supply the ring and pinion, plus crush sleeve, and they do the install.
After you get the pricing you can figure out if you've got enough money, or need to save up first. Summit has pretty good prices on ring and pinions, but you need to know what gear ratio and housing you're using, so you can ask their tech guys what will work for your housing.

 

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I totally agree with this. There's a guy around here that could get the parts and do the job almost for the same price as I almost paid for just the parts. Too bad I had already bought parts but a friend was going to help me do them. I helped where I could and watched when I couldn't help. I would have to say that I would probably need to sit through another rear end or two before I think I would get it 100% right with no problem.

 

I know a mechanic that will put gears in and all seals for 100 dollars plus you buy parts but everybody on this site seem to be very far a part.If you live in north carolina i could hook you up.

 

A 2 series 8.5 inch carrier is 2.56 and down (numerically) gears. A 3 series 8.5 inch carrier is everything above that. Anything above 4.10's (or 4.36, I can't remember which) you have to notch the pin or gears for clearance of the gear's teeth to install the gears. The 8.5 10 bolt is the only carrier that has two carriers without a carrier break above 4.10.

 

Thanks kyph