I have a used ignition lock from my '82 300SD. I bought a new one since I thought that I would have to cut off this old one when I counldn't get the key and tumbler out. Luck had it that I could remove it without ruining it.
Anyone that is having trouble with a stickey ignition key in a diesel should replace the tumbler and key IMMEDIATELY. If you are having trouble with getting out the tumbler you have a 90% chance that you will need the lock mechanism. I waited too long and it cost me and additional $180 for this part.
Here's one for the asking. Send me the shipping cost and I'll help you after my DIYS efforts.
Bob