I purchased this car 2 months ago and the guy who I bought it from said he put a new engine and thats why the miles were unknown, and I wanted to figure out what kind of engine could be in it. ANd after months of searching what the engine number meant. I found out it has a M617.951 300SD Turbodiesel engine. Only problem now is figuring out what year the engine is infact. And how does this car react with this kind of engine, because the tranny wasnt changed, my mechanic did infact have to modify it but he didnt know there was a SD engine in there. I wonder what hes gonna say when I tell him that. Does this engine weigh more than a regualar 300D turbo engine. I found most of my info at IF there is a 300D next to me will I beat him with this car lol. I can tell you one thing ive done 0-60 in 9 seconds or less. this car has some juice in her since my tranny is modified and I have a new injection pump with special adjustments. And Im finally getting good MPG 450 miles every tank full to the reserve light. I do know that the old engine did have 250,000 miles but the car itself is mint. The odometer reads 86,000 miles because the previous owner changed the speedometer with the 1985 model that had 0-120MPH. Ive done 115mph in this car, I wonder if the speedometer is accurate. As I slow down after getting off the highway a guy racing next to me says **** what kind of diesel is that, I couldnt catch up to you. It feels good to beat someone in a 5 cylinder diesel while there driving an new V6 or sometimes a V8, they just cant handle those turns like I can ..