I've just got the single exhaust system on my machine and I need to replace the donut gaskets. They're leaking like a sieve. Is there a replacement donut gasket that I can get as Autozone or O'Reilly's or something? I've hear that you can use part # 31360 from them but it doesn't look the same as to what the factory one looks like. The factory gasket has two indentations underneath whereas the other donut gaskets don't share that characteristic. Please help! Hoping to go riding by Friday!!