Hi I got a rf400 and over the winter I'm replacing the valve stem oil seals found the seals ok but I'm finding it really hard to find a head gasket the engine is a gk78a would anyone know where I could get one or if the engine is used in any other bikes I've found the bandit 400 has gk75a but someone says they are the same head gasket no sure if this right or not I would be very grateful for any help