Technical 9.3 Pontiac/Olds. rear end

I think I know the answer to this but here goes. 57/58 rears are 29 spline and 59-64 are 31 spline. Question is can the spiders be switched from one carrier to another to fit your needs? 29 spline or 31 spline. Or is a carrier with 3.23 gears the same carrier with 2.87 gears? I'm running 29 spline and 2.23 gears in a 57 Olds. and want to go down numerically (higher ratio) like 2.87. Dealing with open rear.

 

Fabcraft do them and would be know

 

????

 

I have all of those rears and a 31 spline axle will not physically fit in the 29 spline carrier. At least when I tried it, that's how I easily identify them.

Pat

 

Yes you can switch the side gears. But you can also switch axles, they are not real spendy but you-might need axle bearings...

 

What 1934coupe said.

I gave it a try myself, many years back, had to buy a new posi unit and later 31 spline axles. I bought the posi unit new, the axles were wreaking yard pieces.
The 29's are pretty wimpy anyway ! They twist easily.

Mike

 

I do realize a 31 spline axle won't fit a 29 spline spider and vise versa. The question made a little clearer will a 1957 carrier fit in a 1960 third member? This is a 57 Olds. I am working on. I don't care about strength. If all the horses are awake on a good day there is only 300 of them if I'm lucky.

 

So you want to put early spider/axle gear into a later carrier?

 

A 57 carrier (the thing that holds the ring gear) will fit in the 60 third member (the cast iron chunk that holds the pinion).

Pat

 

I removed a 1957 Olds 3.42 gear at a pik-a-part and tried to put it in the rear end of my 40 Chevrolet race car. I didn’t count the splines. Obviously it didn’t fit. I removed it and replaced the spiders with a set from a 2.69 pumpkin. The Olds pumpkin fit in the later Pontiac just fine. All was good.

 

Yes Pat. you are correct. Maybe I phrased my post wrong initially. My 1957 Oldsmobile has 29 spline axles and 3.23 gears. I am acquiring 1960 drop out section with 2.87 gears. I want to use my 29 spline carrier in place of the 1960 carrier in the pumpkin hogs head or what ever you want to call it. So my axles fit. Or just change the side gears to achieve 29 spline for the 57 Olds. axles. And I am not changing axles or axle housing. Just the drop out and make it accept 29 spline axles. I am going to use 29 spline axles. I want to achieve a more friendly highway gear as the hydro. has such a low 1st. gear anyway. I hope this cleared up the confusion.