42RH / A-500 in a Duster with pictures.

Since the 42RH is essentially a 904, will the Turbo Action Cheetah full manual reverse pattern valve body from my 904 work with the 42RH?

Since the O/D and L/U are electric, I assume my old Hurst Pro-Matic 2 will still work, yes/no?

The RH/RE transmissions must have a designed for valve body. (Solenoids for LU/ OD are part of the VB) I believe your shifter is fine