Banana---I have a lot of Yamaha's older catalogs and they specifically cover the "vintage finish" in their text. It's actually a "resin oil" they apply by hand and the drums actually sit in their shop for several months to obtain this "aged" look that is instantly classic. Of course, Yamaha will never divulge that in-house secret as to what brand resin they use, but I'd say check with some wood finishing stores if you have any in your area--simply google "wood finishing"-- and ask them if they know of anything they offer that might offer the same or close results. It will be a product that is amber looking while in the can and they should be able to help you locate an "aging" product. Probably not exactly what Yamaha uses but close enough to achieve the desired result. While you're at it, google "yamaha vintage finish".