The vacuum pump on my 82 6.2 leaks oil where the vacuum canister attaches to the drive housing.
Not sure wat type of seal is supposed to be in there as mine was missing.
Dealer doesn't have a listing for a seal. Neither does Napa or any other auto parts stores. Tried all local diesel shops. I went to the local bearing shop and tried various o rings and seals, but none are correct and oil pours out.
Any idea where I can get a seal, or where I can get an idea what the original looks like so I can give the guy at the bearing shop a better idea what to sell me?
Many thanks!

It's an o-ring. Small diameter, like an Air Conditioning pressure hose would use. I've replaced them in my own vehicles, but never for a customer. Always bought a new vacuum pump because the diaphram also had oil coming out the vent. I bought mine from NAPA out of the NapaTemp A/C catalog.