Greg,

There may later technical bulletins if the gasket design or the head bolt design changed for the 1975 240D engine, but the manual I have is from late 1977, and makes no mention of the bolt stretching technique you described. It says recheck the fasterners after some 300 to 1000 km.

I know some of the later cars were built with head gaskets that no longer required the follow up torque check. I am not aware of the practice of backfitting such gaskets to the earlier cars, but think it would be a good idea. The head and block mating surfaces are likely ok for the newer gasket, but I would check the technical bulletins before I did that.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)