Is there any way to tell how many splins you have without opening the carrier?

 

If you have a stock 10 bolt in your '90 it should be 28 spline. I think the 26 to 28 swap was mid-year 88.

Anyone else know for sure?

- Justin

 

You be right brotha

 

Depends on your axle ratio, you never know what GM had inventory. Mid to late 89 was the start of the change from 26 to 28. Unless you have a low ratio and a Limited Slip I wouldn't bet on it.

 

I dont know man,I've heard the change was in 88 and I've been hearing if for years around various message boards.

 

I have the 2.73 or 2.77 rear end, not sure exactly which one it is. So you fellas pretty much say its the 28 spline set up? I need to know ASAP. Another question if I order the posi unti from Thunder Racing I should be able to swap the gears also correct? What else should I double check? I plan on swapping in some 3.42 at the same time.

 

Being a 90 you will have 28 spline axles.

While your in there I would put in all new bearings.

Dont forget the posi unit additive!

 

With the old unit being a series 2 carrier, the posi unit is series 3, will this fit with new series 3 gears and bearing kit?

 

The changeover may have started in 1988 production, BUT it was for model year 1989 and NOT for 88 models. Thats why you are confused.

 

Before you do anything, determine what rear you have a 9 or 10 bolt. Because parts are NOT INTERCHANGEABLE betwween them.

 

late 89 was switch over from 26 to 28 spline axles. Every 89 ive seen, including my own, has 26 spline axles tho. 90 will be 28.

 

I've got the 10 bolt rear end. So it's safe to say I have 28 splines?

 

yes if its a camaro, im not sure about the pontiacs but its probably the same thing you gotta find that out for yourself.