[Big Dave]

If you can get a T-56 cheap I'd recommend doing it.

As you said, a number of people have swapped manuals into Panthers. It ain't easy but Mustang master/slave cylinder kits help a lot.

The T-56 will tolerate massive torque - they are common in Corvettes, vipers, and performance Mustangs. This massive torque rating translates into a very, very reliable transmission for a low-power ecomodder, and as an ecomodder you can get away with a very light clutch. Also they are available with a truly massive overdrive top gear - either 0.67:1 or 0.5:1. Lower engine speed at a given road speed equals lower air flow and engine frictional losses. Mucho efficiency.

I would beware of engine-off coasting with an automatic. With the engine off, you are getting no tranny fluid flow through the cooler.

This project is so right. I didn't know that vintage of Panther had such a good Cd.