AMC 20 is bad, the ring and pinion is good, who cares about strong R&P if the shafts and housing shell out?
Yes, they can be trussed, yes 1 piece shafts are available.
Sell the detroit to a guy with a AMX who cares.

Dana 60 and never look back.
But is must be a custom d60 (like I build)because there are none in the wild with the right width, 35 splines, disc brakes, wheel pattern ect...

Let me know If you want a quote.

SD