Sorry for posting, but I need to ask. I did read to try and find my answer but I am still unsure.

I was reading 82-89 is 26 spline (assume that means the same thing as teeth?), and 90+ is 28 spline.

So, I have a 90 rs with the stock open 3.08, and I may be able to buy a posi from a 87 z28. I am wondering, can I just take the cover off the 87 and take the gearing out and put it in the 90rs, or do i have to have the axles too, in order for the swap to work and have posi-trac when its in? Sorry if its a redundant question, I just wanted to know the answer, and thank-you in advance for taking the time to reply and explain. Thanks.

 

You need to make sure if it's a 9bolt or 10 bolt rear. All 9bolts are 28 spline axles. Splines are not the teeth on a ring gear. Splines are on the end of the axle that slides into the carrier. The carrier is what the ring gear bolts to. You also need to swap out the pinion gear along with the ring gear.

 

ok, this is helping. So what do I have to yank out of the 87 to make it all work? I plan on visiting the area where the car is, and would only have simple tools.

 

First of all what are you replacing your 3.08 with? Second, you would be far better off doing a complete rear end swap. Can you get the complete rear end, or just the internals? As far as replacing the ring gear and pinion gear, It is a very complex job that requires special tools and shims to make it right, or you will ruin the gears and axles. I don't mean to sound disrespectful, but i don't want you to get hurt and or wreck your car.

 

Easiest is to just take the whole rear.

 

I didnt get the impression of you being disrespectful at all, dont worry. I guess I will just leave it alone then. Getting the entire rear is not going to be possible since I wouldnt be able to fit it in my car. I dont really know what rear it is, I am assuming its a 3.23 posi but i dont know for certain. I am just interested in a posi rear, not really concerned about the ratio, more to limit body twisting more than anything

i am in ontario canada and would be driving the rs to new brunswick, its about 1200 km or 900 miles or so, and I could buy the rear, I thought it was a simple grab and go but if its best to have the entire thing i will just leave it be and worry about it later when I can get the whole thing.

 

What you might want to do is look for a used rear end with a 3.27 or 3.42 posi. As for your rear in your car, count the number of bolts on the differential cover to determine if it's a 9bolt or a 10bolt.

 

I will do that. Mods can delete this thread, thanks alot for the quick and helpful info. I will keep looking for something locally here in Ontario.