I recently bought a 1985 500Sel. A very nice car, the previous owners put an engine in it with 42,000 miles on it. And they said they bought it and the transmission was bad and they had it rebuilt. They didn't drive it after they rebuilt it. It runs pretty good, but under hard acceleration it slips between 2nd and 3rd gear. This is what my grandpa told me after he test drove it. Since this is a rebuilt transmission what do you think the problem could be?

Who spends all that money exchanging the motor and then rebuilding the transmission and not drive it, then sells it. Sounds like someting fishy about the previous owner's story. Any reciept's for the tranny rebuild job? Still might be under warranty "if" it was rebuilt.

Transmission fluid was a couple quarts low, seems to be just fine now. They have proof that transmission was rebuilt also