Sorry to hear. Re-reading your first post, I wonder if the piston just recently popped when you drained out the old diesel fuel and fired it up.

If the vehicle itelf is in decent shape, you might consider not giving up. Maybe replacing the motor. Really hate to see these fine old Mercedes going to the crusher.

I am the original owner of an '81 300SD and just recently spent some bucks to have the driver's seat repaired and recovered. And plan to polish the hood out this week. Do not ever plan to send it to the crusher.