Hell, the '78 300D can be practically anything.... 115, 116 or 123.

I think the 116 will take any MB engine you want including the 4, 5, 6 or 8 cylinder - it doesnt matter because bell housings and engine mounts are the same, but final drive ratios will differ.

Both the 115 and 123 have never had an 8, so you will probably be fighting subframe and engine bay clearances there. Especially think about clearances for the manifolds.

We usually laugh at people who throw Chevy V-8's into the MB as if the Mercedes engine is the worst part of the car, but lately somebody came in here with an excellent Chevy conversion into a 108. He knew what he was doing and has contributed alot of info on this conversion idea, almost matching original MB specs for engine weight and torque.

Surf back a few pages and you will find the multi-page thread and can wake it up to get exact details. Respond and it will be kicked to the top of the list. Around here it usally takes at least a week for threads to get past page one, so nothing gets lost.

He said he used the original MB tansmission and drivetrain. I think his name was Mercedes_68.