I have a 1980 500SE with the basic 5.0l AMG engine and a Gleason rear diff of unknown ratio (one of these days I'll have to find the dumb thing but 25 years or grime make it no easy task) and a stock tranny from something. The previous owner seemed to have no idea this car was an AMG so she slapped in a used tranny a couple of years ago and all the paperwork says is W126 tranny. Anyway, it is generally fine but under heavy acceleration (not max) the thing will up shift WAY too early, especially into 3rd. And I mean WAY too early, like at about 1/2 the speed i would manually do it. So my question is- is it a problem in the tranny itself or is it a conflict with the rear diff ratio that is causing this. Thanks.

John

'80 500 SE AMG
'80 300 SD