drive shaft

It will depend on which A-body. Wheelbases varied - 108 & 111 on the later ones.

I do have a 45" driveshaft for sale which may work in a 108" wheelbase Duster/Demon/Dart. But the best way is to mock it up & measure.

http://www.forabodiesonly.com/mopar/showthread.php?t=246906&highlight=driveshaft