I have a 77 Mercury Cougar. It has a 351m, which as far as powerplants go, is a sad puppy. It's an engine that gets small block power with big block fuel economy, the worst of both worlds.
I don't want to pull the engine since it works fine, but the 351's status as a big block means that my choices are limited when it comes to alternative transmissions. Problem is, I don't know what my choices are. I've heard something about a 5 speed for trucks that might work, and on the $$$ side I've heard about people getting adapter plates and pulling a AOD from a crown vic, but past that, nothing. I want the most driveable transmission for the buck, and I need ideas about the application and the cost.
bulletcatcher, I believe the trans you want is the E4OD. They should be quite plentiful. I don't know what type of trans controller you will need. Baumann Engineering may have a solution. I could be completely wrong as I'm pulling all of this from the deep dark recesses of my brain.
Call up a local auto wrecking yard and ask them to tell what interchanges from their Hollander manual: they're usually quite helpful to tell you. If the first 'yard isn't helpful, call another, and another until you find one that is.