300SL-D?
 

Very odd combination. Strangely appealing to me.

I think there are some potential problems with this conversion.

He's in California and the vehicle is allegedly "calif clean title diesel car in non op". I would question how he got a the OM617.x engine approved in a '91 car as the last year for the OM617s was '85. It may not even be a CA engine with the trap oxidizer.

The law and regs, in a nutshell say that a gas to diesel conversion is allowed provided

(1) the replacement engine is from the same year or newer
(2) the engine has all the smog equipment originally with the car
(3) the engine is from a "like" vehicle (meaning you can't put a light truck diesel in a passenger car, etc.)

I'm not saying it can't be done, but if it's real, there has got to be a back story - like it was converted out of state and brought into CA as a diesel car and then registered, which would actually work, because diesels are exempt from smog so it would never be inspected again. (Actually, this very well may be the case. The license plate on the car does not look like a CA plate - maybe Oregon??) Or somebody could have put a '91 or later diesel in, got it inspected and the title changed and then replaced with the 617.

For posterity here's the pics from the Craigslist post.

http://www.mach4.com/images/stories/380sl/dslsl.jpg

Or he just got lucky and some bureaucrat looked at it and said "sure enough it sounds like a diesel, smells like a diesel and looks like a diesel" and made the paperwork change. It does happen - I know someone that had a fiberglas version of a classic car that was mistakenly registered as a "real" classic by an unknowing DMV employee that just saw the name of the car and unilaterally changed the paperwork so it is now titled as a "classic plate" car, exempt from everything.

There are several potential red flags on this vehicle that any potential buyer should check out carefully!