Overdrive auto for a 383 72 Dart

Whatever you use will need an adapter plate, unless you use the Mopar 833 4 speed manual OD transmission. If it was me, I would use the GM 200R4. Opinions vary.

200R4 all day and day. If you have to cut the tranny tunnel (which you don't for the 200R4) why limit yourself to a 4 speed when you can drop in a 6 speed.