This sealing ring is intended to replace the listed oil filler pieces between the oil filler piece and the alternator bracket or as a seal in the oil cap depending on whether you have an oil filler piece or a crankcase ventilation tower.
The crankcase breather tower oil plug uses the same sealing ring as used in the straight and the 45-degree oil filler pieces between the filler piece and the crankcase.
The sealing ring for the 45-degree straight oil filler piece oil plugs is a little larger and also replaces the flat rubber or cork gasket used on some factory oil filler plugs.
So there are two sizes, on the "other models" tab the other seal ring is listed.
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