I replaced my left side crankcase cover on my 2007 WR450F this weekend with a brand new one after my shifter got pushed through my old one and broke it. After putting everything back together and cleaning up, I found a small O-ring in the bottom of the oil drain pan that I believe to be #10 as shown on the attached parts diagram as supplied by Partzilla. This Partzilla diagram shows the o-ring on the outside of the gasket on the cover side. However, when I look in the service manual it shows the o-ring on the inside of the gasket on the engine side. So I have 2 questions: 1. Which side of the gasket should the O-ring be placed? 2. Is it even necessary? I know the dowel-pin is in its place and with the new gasket nothing is leaking (it’s a dry sump anyway). When I look at the old cover it does not seem to have a recess where the o-ring would fit into around the dowel; and I recall the dowel-pin fitting snuggly into the engine side. So I am kinda confused about the use of a gasket and an o-ring at the same time; can anyone help? Thanks!