bpossel: Just replaced the oil and oil filter on my '66 230 SL and used MANN oil filter no. H 720 which, in its package, includes large diam. o-ring for groove between filter container and its mount on engine and an alloy washer for between filter container and long bolt which secures container to mount on engine.
If you do the task yourself, you may notice like I did that MANN is stamped into the alloy (OEM of course) filter canister.
P.S. I'm an acquaintance of Pat Williams in Memphis and I live in Bowling Green. He's a Porsche tuner and if you don't know him, you ought to go by his shop and see his client's '76 911 race car conversion - it was unbeatable last year...