OK so one of my friends has a '74 camaro that he just droped in a 454 and he has the stock rear end and he wants to use the stock housing and use 12 bolt axle shafts and us 3.50 gears and a posi. I don't think it will work but then again i am a ford guy, but i have built some kick *** chevy racing engine.

 

They won't work. The 10 bolt 8.5 has 28 splines while the 12 has 30.

 

You can get a 30 spline posi unit for you 10 bolt. This will allow you to use the 12 bolt axles. But you will have to shave the C clips about 1/16" The only thing I'm not sure about is the axle bearin dimensions, and if they are the same between 10 and 12 bolts.

Try giving Tom's Differentials a call.

Good luck.

 

yeah i was telling him I don't think the bearings will allow him to do it. I am trying to get him to just buy a 9" and install it.

 

9" and 12 bolt = same thing. I'm building a GM 10 bolt 8.5 for a lot less than one of those. How much power does he plan on running?

 

Just tell him to get a set of alloy axles for the 10 bolt and be done with it. If the 10 bolt blows, get a 12 bolt. The 9" Ford can handle a little more torque than the 12 bolt GM, but because of the lower location of the pinion has more drag and sops up more power. If you really want to get strong, go to a salvage yard an pick up an axle from a 3/4 ton GM pick up truck. They come with huge gears, semi floating axles that can be removed with the wheels on, and big gear ratios.

 

well the 10 bolt will blow, he just got his engine dynoed and it pulled 668hp and he has a line on a 9" so i think he is going to do that one.

 

I was gonna say that HotRod's next issue has a deal about bulet proffing your ten bolt coming up in the next issue, but with those numbers he will want to put in a 12 bolt or a 9"

 

Yea, I saw the bulletproof 12 bolt but I dont have a 12 bolt. I just bought a 10 bolt 4:11 rear that I am going to install soon.