I was thinking that the 18R-C head gasket would fit the 18R-G because they have the same block, even though the heads are completley different they are the same at the bottom where the block and head meet. A difference i have noticed in the rc and rg heads is the rg dosent have water holes that match up to the water holes on the block just near the head bolt holes, the rc head has matching holes so the water flows through. Anyway is anyone sure that the gaskets are compatible, i do know the head torque settings are definetly lower the the R-G, bout 65lbs