Overdrive or don't worry about it? !

Sitting here on the patio on a pleasant, breezy Sunday morning is a great time to spend other people's money.

I think you should stay with the 3.55 and add OD. It just makes for a more enjoyable driver. I find it better to do things like this right from the beginning instead of later and it sounds like you are going to keep this car a long time. Like updating or adding a bath to a house, an OD adds value to your car if done properly. You may not get every dollar out of it but it's something. And everyone raise your hand if you think gas prices are going to drop again. The present administration has made it clear they are going green. All they have to do is raise federal taxes substantially to cut emissions.

GV is a proven product but don't forget about the driveshaft change.

All Mopar would mean a swap to a newer 4 speed OD.

Nobody has mentioned the bolt-in automatic OD offered by Silver Sport Transmission. It's based on a modified GM trans. Another alternative.