Perhaps she's not a goner after all..

I'm leaning towards a trans problem myself.

I have a car with a 904 that has a trans problem. If I put it in gear it will move, but if I give it gas at all the trans "screeches", ut will accelerate at idle until it shifts to second. If, after it shifts to second, I lightly gas it, it will pick up speed without problem and shift into drive also with no problem, although all under minimal acceleration. My problem could be similar to yours due to the screeching. I believe my problem is that the low/reverse band is worn to the point where a trip into the trans is the only repair!!
Could this be related to your problem?? I offer that it may!!

Now, if I were you, and it sounds like you have a good understanding of how things are under your car, and could detect something amiss!! Therefore, I would spend some time under there. Take off the inspection cover and check the converter bolts...jack it up and check things as mentioned above, and most of all look for any evidence that something happened. Something like a fluid leak, rounded heads on a bolt or something of that nature. Take the rear wheels off the car and remove the drums before you turn the rearend and listen and feel how it's spinning. Grinding, end play on the axles, anything in the drivetrain that is suspect should be checked before opening anything up or assuming that it is something that it may not be, costing you $$ and time!!

Just trying to help and by no means a trans expert, I just spend a lot of time under my cars. Heck I was even thinking about throwing out the matress in the bedroom and just sleeping on cardboard!! Good luck and report back!! Geof