The Dodge Challenger Message Board

So I dug up an old 8 3/4 rear end that was in my barn. It had a posi chuck in it, so I figured I'd do a quick swap for my chuck this afternoon. The rear end was out of a 70 Cuda, so of course I didnt really measure anything beyond making sure it was the same housing. I got my car up in the air and unbolted axles and everything, (thank god didnt crack the seals, that would have been a hell of a mess for nothing), but when I pulled the yoke off, it was different splines. The yoke on the posi rearend was coarse splined, and the yoke on my car was fine splined, and on top of that, the width of the yokes was different across the inside by half an inch. I have to EDM a snapped bolt out of the posi yoke, too, if I'm to use it.

Should I use a different size U-bolt if I'm able to re-thread the posi yoke? Should I be looking for a different yoke or driveshaft? Also, are the axles going to be the same for both rear ends, or will they be splined differently too? In that case, I would have to swap axles with the posi rear too. Just looking for suggestions before I go and bugger things up again.

if the axels are the same spline you could just swap the posi center into your chunk using your original ring gear if you dont plan on changing the ratio
cheers ian

The ring gear is held to the suregrip with left hand thread bolts. It is easy to swap them over and re-use your ring gear but you will have to re-set the bearing preload and back-lash using the workshop manual instructions TO THE LETTER!

Thanks Ian and Dave.

I wanted to go with the 3.90 gears that are in the posi, as mine currently are the 2.7-something highway gears. It'd be a lot of work for nothing if I had a posi with 2.73 gears! I am on the hunt for a coarse splined yoke that will fit my driveshaft. I've been told I can get u-joints that will fit my driveshaft but have longer ends to adapt to the other yoke, but there's a big difference in yoke size and I'm not sure that I want to go that route.

Any way I could know for sure if the axles are the same spline, also, with my rearend still together under the car?

Here's a great supplier of hard to find yokes, u-joints, all MoPar permutations you can think of. www.hensleyperformance.com ask for Matt or Ken they are very helpful. Good Luck

Thanks Eddie, I'll see if they can help me!