I'm looking at upgrading my 8.5" 10 bolt in my 1971 cutlass to a posi unit, 30 spline axles, and 3.42 gears. I had monzaz give me a quote for parts(thanks again Jim) and axles are spendy! I found these axles on Rockauto for $59 each bare. If I can press on my own bearings and studs, is there any downside to these? The axle length of 29.625" matches my current 28 spline axles. I'm dreaming for a target 600ftlbs of torque at the flexplate in the future.

 

Yeah, the correct axles are expensive for a reason - they're special order.

Check with Jim or Brian, but I don't think this will work out. Looks like those are normal C clip axles. So in addition to the nubbin for the C clip, I'm not sure if the bearing race diameter is the same between the press on bearings and the axle tube mounted bearings.

Assuming you have the original bolt-in axle 8.5", finding correct axles is tough because everyone seems to have forgotten about those rears. They weren't made very long and seems back-in-the-day folks threw them away in favor of a chevy 12 bolt as soon as they could.

Now, if you have a C-clip rear, then rock on. I do find it funny that the description says the bolt pattern is a 6x4.75 though.

 

Oddball, any reason what would tip you off to c clip axles? I came across this axle by searching for my specific vehicle on rockauto. I also notice that the spline count is listed as 30 in one place and 31 in another. With all the typos in the part description, I may need to inquire of Dana using the listed part number and see what they have to say. Although the length matches, who knows where they are measuring from. I am measuring from the outside surface of the axle flange to the end of the splines.

EDIT: I see on the second pic the provision for a c clip. However the pic appears to be generic and used in other axle descriptions as well.

 

So, my ignorance keeps coming out. To clarify, 12 bolt and 10 bolt axles are not interchangeable. Correct me if I'm wrong, but no 12 bolt diffs came with bolt in axles, they all use c clips. So there are no stock swap options to a 30 spline axle for a bolt in style diff. Even if one could grind off the c clip "button" on the end, the wheel bearing axle surfaces are not the same between a c clip and bolt in, right? Aftermarket axles are the only option for bolt in 30 spline axles in a 8.5" 10 bolt.