The 2 thin halves with the squared off ends that go above the crank/above the #5 main cap OR the rear pan seal with the tapered edges? the 2nd one I am thinking. I have no 340 exp but the #5 rear main cap is different on a 318 than it is on a 360 & may take a specific one. I think a person could after mocking up if one is too long & wont set flush in the groove & that is to cut a piece off away from the tapered edges of course to shorten it so it will set flush in the wide shallow groove on the main cap then seal that junction with some silicone. otherwise here is a BTT for ya. EDIT How loose is it? my 360 one was a slight bit loose, like it did not want to lay dead flush in the wide shallow groove but with some sealant under it it sealed up OK (no leaks).