I'm considering an A 500 4 speed overdrive for a 72 Duster

chargerz said
ocdart, where can i read on the GM 200-4R swap !?

There are several build threads using the 200-4R. Here's the first one I found...1969 Dart Street/Strip (Re)Build

Suggest you also check for 200-4R install threads from FABO member jbc 426.