I've got a bit of a problem on my hands in that I want to get an oil pump back on the MC21 engine for road use (dry clutch, in an MC18 frame) but I can't figure out if I've bought the right oil pump. As clarification, I already had two MC18 oil pumps for the extra engines I have, but I was hoping to get this Dry clutch engine working first. Anyway, I bought a MC21 oil pump (from eBay) and it looks identical to the MC18 oil pumps I already have. I know the MC21 is supposed to have an oil feed down to the RH bearing and the "MC21" oil pump I purchased doesn't fit over the hole. And looking at the parts diagrams, it's all one unit too. So I'm suspecting I've bought another MC18 oil pump due to the seller incorrectly listing it or sending me the wrong item.

Just to confirm: The MC21 and MC18 oil pumps are completely different? Does anyone have a picture of an MC21oil pump picture up close? I have assumed they're different from the differing part numbers, but I know sometimes Honda has different part numbers for the same things.