727-904 REVERSE SLAMS HARD WHEN SELECTED

GTS Dave said
Agreed.. My mechanic stated the exact same response regarding my 340 Duster/727 tranny. After starting engine, go to neutral for a min, then drop into drive once or twice before going into reverse. This is especially so if you have a shift kit.

This gets the fluids moving around. Old cars are like old guys, things need a bit loosening up before kickin' it in gear..

I got this same advise from a trans builder who was a Mopar dealer transmission guy back in the day. His advise was the same, get it off high idle, pull it into drive, then into reverse. No bang going into reverse. He said that this was a major cause for the lugs breaking off the reverse bands.