Need some schooling on transmission compantability.
 

OK this is for my SEC diesel project. the donor is a 91 560SEC and it comes with a recently rebuilt tranny so I would prefer that one over the tranny that is bolted to the 617 goin into it. SO since its already in there Idont have to worry about speedo sending units and such but what about gearing, vacuum signal and other things i am not thinking about right now. What are the issues to look into?

91 sec is going to have computer controlling shifts etc... I think you are going to have issues.

More issues
 

The starter for the 617 will be on the wrong side to work with that tranmission and bell housing.

and there's that...

Hmm, These sound like some significant issues. not what i wanted to hear. Well worst case I will have to use the diesel tranny and work around other, smaller issues, but man I wish there was a way to take advantage of this thing.

Bellhousing is different between V engines and inline engines.

Also, your SEC will have an eletric speedo. If your donor driveline is not out of a W126, you'll have to change the tailshaft.

Jim