I bought a used Q-500 with a Rossi .40 five years ago and it's been sitting in my closet until last weekend. I decided to dust it off and sell it, but the Rossi takes a plug with an o.d. that's slightly larger than a standard plug. I know nothing about Rossi engines, but this one has a gold head. Is that an aftermarket head, and if so, does anyone know what plug this could possibly be and where I could get one? Thanks for your help.