Did think that too but having stripped my bus recently I know its not from that area. That piece that's on your pic has a horse emblem on it (a bit like the Ferrari badge) and is quite rigid plastic whereas the piece I am unsure of is quite supple. Thanks for replying though (my bus is a Westy though).
It's off a westy. Fitted on the steel roof above the sink unit where the vent pipe goes through.i d take a picture but haven't got the van at the moment
The seal is an original Westfalia part, the other part looks home made, the original is hard plastic with the Westfalia ( Standing Horse logo) logo on it, it fits to tin top or pop top roof for stench pipe vent.
Later buses had them on the side to vent the sink pipe work.