I'm not sure about that one, I'm very tempted to say it's a RG550DY re-issue with a retrofitted pickguard, maybe custom made or maybe from another guitar.
The RG550DX stopped production before 99, 93 was their last year, if I recall correctly, having been replaced with the RG550LTD which of course had shark tooth inlay. the replacement to the RG550LTD, the RG550EX have rosewood board and I don't think came in till 2000.
However, I do recall a batch of RG550's being made with similar coloured guards for "Musical Exchanges" a few years ago. But they had snake inlays and gold hardware, definately not one of these. So yep I'll go with my firsty suggestion, and RG550DY with a different guard, whether this is a modification, or a factory upgrade I can't tell you.