Not sure if I am starting something here...
But my '81 300TD-T has had the rear leveling system disconnected and standard shocks in their place.
Maybe this would be a good time for you (wagony)to do the same?
Might save you a little headache finding a good engine, and also down the line when the rear leveling goes out on you.

I did not do it myself. The PO had it done.
Not sure how he went about it, but I enjoy it. Very nice ride too...

__________________
Current: '91 300TE 4MATIC 317k and climbing...
Former:
'81 300TD Wagon 168K "Tank"
'83 240D 216K 4spd manual "Da Bear" (aka best car ever)

"Never sweat the petty things...
and never pet the sweaty things."