I've converted my car to a 700r4. It's very possible the slim jim trans is still good except for the front pump. The problem that started this was, I could drive ok, but as soon as I needed to go up a grade at all, it wouldn't go. Engine would just rev in drive. Prior to that, it didn't actually slip while in gears. The trans has very low miles on it from the get go. The car had an Edelbrock carb which of course doesn't have the correct linkage for that trans. I think thats what may have finished it off.
For the trans....basicly pay shipping and $100 (for the effort of boxing it and dragging it down to the freight place) it's yours. Yoke included.

Shifter parts- I used the upper handle portion to graft onto a Camaro shifter to get proper 700r4 operation. The base, under carriage parts, neutral safety, etc are still good. Make offer.
916-248-1402