over drive trans

If it's just for gas, the lockup 727/904s are decent and require nothing but the switch. That's not hard to set up either. The next cheapest is the Gear Vendors unit. I consider that a deal at $2500 and it is basically a bolt in. I'm not a fan of the GM transmissions in my mopars. More of a personal taste thing than anything technical but the adaptors do add to the cost dramatically.