Like the title says, I am looking to swap the engine and trans (and possible rear end, and other components) into a W123 300D wagon. Why do this? I want to get maximum MPG out of a car that can cruise steadily at higher speeds and still have power on tap to make passes while retaining a pre-1985 body.

The swap parts would most likely come from a E250 CDI BlueEFFICIENCY.

I have only seen one article about a swap like this, and it was preformed by Mercedes themselves when swapping the same engine into a 1992 190D. Link here

I am not familiar with the CAN BUS network, but would be interested in learning about how to make the swap work.

TIA for any help