The transmission from a W124 won't work. The starter is on the wrong side. They did sell the 240D and 300D with five speed manual transmissions, but not in the United States. A very small number of grey market cars with 5-speeds were imported to the States. These are the potential donors. I read on here not that long ago that you can still buy a new 5-speed from Mercedes, but they run somewhere north of seven thousand dollars.

Swapping a 617 into a 240D is certainly possible, and people on this forum have done it. However, in my opinion it's much easier to simply buy a 300D if you're wanting a 5-cylinder.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.