Module on back of transmission?

I've been fighting with my 96 Windstar for about a month now. My husband finally took it to a wreckers to see about selling it to them for parts. When he came back he said the workers there played with it for a few minutes and were able to get it into reverse and that it's not the torque converter but a "module" on the back of the transmission. I can't remember what he called it exactly but I know that if you're standing at the front of the vechile facing the rear it's on the back and it's round.

The problem I'm having is that the engine starts and idles fine in park and neutral, and we're able to shift it into 1st gear (then into 2nd while driving) but it stalls when put into reverse or drive. Also, when it's jacked up with the brakes pulled off you can change through every gear fine. We've changed and checked quite a few things to no avail.

Anyone have any idea what this module is/does and if it's possibly causing the problem?

I forgot to mention that I've had two different readers (can't remember exactly what they were) connected to it and there are no codes coming up at all.

I forgot to mention that I've had two different readers (can't remember exactly what they were) connected to it and there are no codes coming up at all.