Ok. So I'm back after a long absence. I got side tracked on a BMW e21 resoration and have been ignoring my mercs now for about a year. The BMW is in pretty good shape now. it started out as I was going to buy it to restore and flip to make money to fix my 240. But then I drove it and kind of got hooked.

Any ways long story short I am now back to working on my mercs. Specifically I am sitting on all the parts to do a manual 4 speed swap. My big question is regarding flywheels and crankshafts. As I understand it for a w123 the two are dynamically balanced together. Not statically balanced separately. Is this true? Will swapping them cause problems? I have searched the forums and this question has been asked over and over but I'm curious to hear of any real world experiences with folks who made the swap without pulling the crank and having it balanced to the flywheel. Specifically any noise issues or shorter wear life on the crank. I only want to do this job once. And I plan to drive the car till I'm dead. Should I pull the crank and balance it to the new manual flywheel from another car? The other option is I also have the engine that the manual flywheel came from in my garage on an engine stand and could conceivably pull the matching crank. Or just rebuild that engine and just replace the whole thing. I do know that engine used a lot of oil. A lot of options here but would be interested to here the current thinking regarding the crank flywheel balancing issue.

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1978 Mercedes 240D
1981 Mercedes 240D
1982 Mercedes 240D