MB put the 616 engine in their range of vans 207-407. Someone posted on here at one time that the van engines had different cams which produced more horsepower. I was somewhat skeptical about this because most of the ratings I have seen on the vans were the 44kw, although it is possible that the higher powered motor you refer to was in the vans. If it is the van engine, there are a couple of other differences. The oil filter housing in the van points down and back and is changed from below. It also has a different valve cover and water pump.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13