The early 617.950 engines had a the low power cam, rocker arms and valve springs. They also had no EGR. Later 617.950 engines were at the same power level as the 617.951/2.
The oil pans look different but exchange between all 617.95* engines.
So do the oil filter housings.
The engine mounts differ between body styles, 116, 126, 123.
There may be a difference in the IP, but i am no expert on IPs.

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76 240 D. Bought in 1998 for $25.
85 300D. Got it for free with a bad engine. ( Sold )
60 Unimog 404. What was left of it, was given to me. Now powerd by 617A.
88 560 SEL. Bought without engine and trans. Now powerd by 617A.
67 250 SE. Cuope. For resto or sale.
64 220SE. For resto.