another source for oil getting into the air intake is the vac pump having a torn diaphragm.
Is that Ft Worth place near Billy Bob's BBQ joint? (last place in the area I visited)
There used to be an ad running in every Hemmings MN for a Mercedes parts place in Ft Worth, I'll bet that's it.
FWIW, the hatchback in my '79 300TD uses hex bolts too. I need to replace them (again
)