maybe dumb??s maybe not!!

The 5 speed used with a 3.9L in an 88 Ram is the NPA535, later known as the NV2500. I was the service manager at a Dodge dealer in SoCal when this trans was introduced and remember it well. Unlike The NV3500 it has a separate bell housing. It was also used behind the 2.2L in Dakotas. It is a bulky wide ratio truck style unit and is not near as strong as a 3500. The shifter mounts to a tower atop the trans like most truck trannies. A lot of customers complained that it was noisy, especially in neutral and hard shifting when compared to D50s, Commanches and Jap truck 5 speeds.
For an A body it would be a difficult swap, probably more trouble than it is worth. If I remember correctly this trans was used with a mechanical clutch.