I didn't tear it completely down. I did however take the two cases apart and pulled the planitary gear assembly so you could get a good idea of how it works. Hope you guys like...
A friend had one of these units in a F150 back in the late 70's and it worked great, until he lent the truck to a neighbor to use while moving. It seems the neighbor ignored the instructions to let off the throttle while shifting the unit and instead kept his foot in it. The result was a tow bill and the end of the overdrive unit. I don't remember specifically what broke, but I know that parts availability was non existant. I don't know if he still has the unit laying around or not, might have to look him up and find out.
Talked to the buddy today. He doesn't recall exactly what was all broken inside, but he did say there were lots of loose piece's floating around inside. He said after moving the unit around the shop for a couple years he just threw the whole thing in the trash container. What a waste, I wish I had known!