They put a number of different engines in these vehicles including the 220d and 240d engines. However, the non-bus versions of this particular chassis are called 508 vans (I don't know why the numbers change for the bus version) but the 8 refers to horsepower. The 220d is a 6 and the 240d is a 7 and the 300d is a 9. But I don't think they ever put the 617 in this particular style of van. The 617 is pretty rare in any of the MB vans. Many of them had a 4 cyl direct injection diesel--is it the OM 314 or OM 352 or something like that?
By the way, there's a similar one for sale on Craigslist San Francisco at the moment.

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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