Torque converter. . . thank me later.

 

LOL, that's a little over the top. A simple drain and refill of the trans oil is sufficient to keep the transmission happy. I had never changed the filter on my 92 SC with 249,000 miles and it never had problems with slipping or otherwise. Just kept the trans oil changed every 30,000 which is still overkill imo.
But I think you're way past that here, find a good low mileage used trans or get yours rebuilt and stick to changing the atf more often.

 

The girl is back on the road!

 

What was it? How did you fix it?