New member, Hi. Asked a couple of you from previous post- anybody know if I can use a 380, 500 0r 560 4 speed automatic or even a newer 5 speed automatic behind my 6.9 motor in my Eurospec '79 450SEL/6.9? Would it bolt up? Would like an extra gear. As you know, the 6.9 is a 3 speed...

 

You won't be able to use the newer 5 speeds as they are drive by wire and the modifications would be more then the cars worth. I'm thinking your engine came with a 3 speed auto tranny? The 6.9 engine is a evolution of the 3.8, 4.5 etc. The same basic V8 is still in service today on the ML, but to 21st century specs.

I suspect adapting the an early 4 speed from a later SEL with the same engine could be done. Or a hydrualic 5 speed might be possible. You should go to a Mercedes shop and get a bona fide answers, as I am speculating, they could probably tell you yes or no.