I gave away a chassis with a M110 engine in it for free to a forum member. So to me, it had no value. But he amazingly sold it just a few months later for close to $1000. So the engine is worth somewhere between 0 and $1000.

Depending on the condition of the transmission, someone might pay you $100 for it.

I would encourage you to take videos of the engine running, because I think that could help your efforts to sell it.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).