Hi, I have a '71 W108 280se that's got a diesel OM615 engine in it, with 4 speed manual (originally auto) gearbox. The conversion has been done nicely (started by the PO, finished by me) with custom mounts, exhaust, auto timed glow system with pencil plugs and I've even wired the glow light to the low fuel bulb to keep everything looking stock! I attach photos.

Its been a reliable daily driver for 5 years now, running on 90-100% WVO single tank all of the time. (has to be done in the UK where diesel is now £5 or around $8.10/gallon!)

The trouble is its sloooooooow to the point of being dangerous in some situations.
Now I know I could put a N/A 617 in it, but here in the UK they are getting hard to find in good condition (probably why the PO put a 615 in it!), and the power improvement isn't what I'm looking for. The turbo 617 is near impossible to find here - I know, I've been looking for over a year and haven't seen a single good one!

Does anyone have experience of putting one of the later 60* series diesels in a W108 or even a 123? They are much easier to get hold of and generally in better shape.
I'm guessing I'll have to change the gearbox at the same time but I want to stay with manual (stick shift). Any idea of which engine would be best? It must be a prechamber engine without electronics.

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