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

Bellied out the middle of the old crossmember, heated and welded 3/8 plate around the bottom and sides of the old xmember to add the strength needed. Did it in 1994 and it worked for years without issue.. I just used a chevy style trans mount sandwiched between the 518 top trans mount plate and the xmember itself.
That's interesting! Do you have any photos of the install? How much did you have to modify the trans tunnel and torsion bar crossmember (if any)?