I have a guitar that looks like an RG 550 except for the fact it has two single coils and one humbucker. It has 550m stamped on the back of the neck and 550 stamped on the body where the neck connects but there are no serial numbers. I can send pictures if it would help. The single coils have long lines and not round dots on them. If anyone could help, I would be grateful. Thank you for your time.