I have just purchased a 1984 B350. It only has a 360/3 speed auto. I would like to stick an overdrive unit in, so that I can increase the mileage a bit. Any thoughts on what would be the best for my application. The van is in decent shape, and would definately look into maybe a cummins swap. But I don't have the money for that yet. This is going to be a commuter for club trips so it is going to cover some ground. Any input would greatly be appreciated. Thanks! Lee