As to your second question: Yes, your car has an overhead cam with hydraulic lifters (so you don't have to adjust the valves). I don't have a 190D (although I want one), but I looked this up in Performance Products catalogue.

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1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold