Tranny mount ????'s

Working on my "To Do" and or "Shopping" list. I have a '73 Duster V8 automatic car that I do not have a tranny crossmember for. I also have a complete '73 Duster slant 6 / 3spd parts car. Will the 3spd tranny crossmember work with an auto (727)? I'm feeling a little stupified about these Mopar cars. I know on my '78 Z that the tranny crossmember will work with a 4spd or an auto. Also.....my auto car does not have a drive shaft. Will the drive shaft from the 3spd Duster work in my auto Duster?