It looks like someone swapped the housing to an 01 and put an O-ring on the 01 bolt; keeping the crush washer. I have seen both styles and that bolt is not from an 02. If both of my 1983 300SDs have 02 housings, yours should, too. The reason it does not leak is because of the aluminum seal at the top of the bolt. The second O-ring does not even look to be in a groove.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge