OD auto for a small block??

Exploring ideas after my buddy got his Brand X car running with a OD auto; goes mid 11's at gets 20 mpg. Grrrrrrrrr...

What is the auto behind the small block Durango/Dakota/Ram? A 518A or something...?? These are just a 727 with a 4th gear, right?

I'm sure someone in the aftermarket makes a 2500-3500 converter, BUT what about a manual valve body?? Prefer a reverse VB, but that's probably too much to ask.

What do you know? What are you running in this arena??

Thanks, as usual!!