I have an 89 Rallysport non posi with the stock 2.73 gears. What spline is my rear carrier??

I am not sure if it made the 28 spline cutoff!?!?!?

A guy has a posi rear for sale here and its for 8.5 10bolt GM rear end with 3.5 gears or something like that....

 

No way you are gonna get a 8.5 carrier to fit in your 7.5 case anyway.

 

Thanks man, I have no idea

Also Is there any way to see how many splines my rear end is?? besides taking off the diff cover and taking out the diff itself and counting the axle spline??

Seems like a lot of work just to see what it is.

I am kind of hoping it has the 26 because it will make a 100$ diffrence when I buy an auburn Posi rear end...

 

The majority of 89's are 26 spline. Very late in the production year, they "may" have gotten 28 spline axles and the only way to know on a late production car is to pull the axles and count the splines.

As mentioned above, a posi for an 8.5 won't fit into a 7.5 diff.

 

as stephan mentioned above, the only way to be absolutely sure is to pull an axle and count the splines on it. Even if you knew what the car came with origionally it's still possible that the rear was rebuilt at one point or swapped out for another from a different year car. Chances are it's 26 spline, and if I were placing a bet thats what my money would be on, but if you want to be sure you're ordering the correct part pull and axle and count. Honestly it's a good idea to pop the cover off and take a look at things before you order parts anyway, while you have the axles out take a look at the bearing surfaces on them to make sure they are in good condition, I've personally had to replace axles due to excessive wear on the bearing surface in two different 10bolts I've had, also take a look at the wear pattern on the gears if you plan on reusing them. Chances are the gear lube hasn't been changed in a very long time anyway so servicing it isn't a bad idea. Also make sure you get the correct series carrier for the gears you plan on using.

 

Last Sat I chucked one of my "91" axles in the vise and set a Torsen on it. Sure was loose. Turns out the rear from my 1991 that I've had 10 years had been swapped for a 1985 model before I owned it. Bummer....now I need axle's.

SO check to be sure....

 

www.tomsdifferentials.com has 28 spline third gen axles for $125 each or at least they used to be. Cheap price for 28 spline axles better than factory 28 spline axles. The axles will fit into any third gen 10 bolt housing with a 28 spline carrier.

 

Thanks Stephen

I also found this:


http://store.summitracing.com/partde...5&autoview=sku

 

I have a GM 10 bolt 7.5" 26 spline rear end.

Now I have to get a posi diff and 3.23s.

Then I will be

 

so you took it apart?

 

I just found this....missed it earlier.

http://store.summitracing.com/partde...5&autoview=sku

Sounds pretty good for stronger [?] axles, bearings and seals with [Alloy USA 10 year "No questions asked" manufacturer's warranty. You break it; you will get a new one!]

Anybody have any experience with these?

 

I am 99.99% sure its a 26 spline, the birth date of the car was sept 1988. The car is an 89 though. It wourld be very odd for my 10 bolt to be 28 splines beaing that early in the production line IMO.

 

Agreed. It's a late 88 production year car sold as an 89 so it's highly unlikely it has 28 spline axles unless a previous owner changed the diff which for most cars is unlikely.

 

Ah, so like I said orighinally, you arn't really sure but you are taking an educated guess. Chances are you're right.