It really amazes me on the MB oil filters how much extra stuff needs to be tossed. The steel one you threw away is one example, the other is the filter for the 116/117 V8 engine oil filter, you always get the drain plug seal for both the 107 chassis type drainplug (huge copper seal) and the type used say on the 126 chassis, which is roughly if not exactly the same as the copper one you used on your Diesel. One of them you don't use, the 126 is more popular around here, so usually you toss this big honkin' copper seal ring. When I first started working on MB, I saved them, I'm kind of a saver anyways, but eventually it became clear "a use for these seal rings is not forthcoming" and I tossed them and continue to do so today. I could try saving up a barrel of them and taking them to the recycler, or the MB museum, but doesn't seem worth the shop space it would take up. Seems the best course of action would have been to make sure the drainplug would have remained the same for a given engine type, I would think it would have saved everyone some money. Unless going to the dinky drainplug saved them so much money that.....well, you get it.
Gilly