Quote Originally Posted by Hobby Racer View Post
The axle is a custom one ordered by FFR as it mates the Subaru front inner and the rear outer CV's together on a common shaft. The shaft is not important, it's the splines, tri-lobe, and outer CV cup that are. If you have a Subaru tri-lobe, you need a Subaru cup. Conversely aftermarket units sometimes use re-manufactured Subaru parts and sometimes do not, that's why it's hard to mix and match.

The splines on the FFR shaft are sized for OEM Subaru tri-lobes so if you can't find one at a parts store you may need to order one from Subaru. It will be pricey if you get it from the dealer.
John, I have re-engineering of rear axles in my future, so I am not asking for a friend.
I assume that the OEM front axle assembly is more robust that the OEM rear axle assembly.
FFR used the inner parts of front axle and the outer parts of the rear axle creating a b-terd and sourcing issues like Mark's.
Is it physically possible (with axle bearing & hub?) to run all front axle components through the upright to the wheel hub?
It leads me to speculate about the choice to not run front uprights in the rear, eliminating this mix-complexity.
jim