I've twisted the splines on 8 3/4 reworked truck axles (cut and splined at Mosier) I thought it was the spool. 10” Hoosiers. I would think someone offers a quality axle. Running an 833 with sintered copper clutch behind my 365 ci La.
Stock axles have to be annealed (softened) before they can be re-
splined. Then you have to depend on how well they get re-hardened.
I twisted splines bad in the narrowed re-splined 8 3/4 I had in my V8 vega..... with a weak 327, turbo 350, and STREET tires. Probably 300 hp to the wheels. Maybe.
My axles clearly did not get re-hardened properly.
If you are gonna try to make an 8 3/4 live behind ANY kind of stick, I think good alloy axles should be the FIRST mod.