Does anyone here know what authentication service the following serial number #UDP16739 might have come from? I just acquired a small hodge podge collection of cards and memorabilia, and included was a hockey puck. The guy I bought it from thought it was just a gimmick thing. However, after researching it, it appears to be a Gordie Howe signed Game-Used puck. And the affixed sticker seems to suggest that as well, and the signature is 100% identical to every signature of Howe's that I've seen, both in person and during research. However, I can't find any authentication services that use UDP in their serial numbering so I can't be 100% sure it's legit. I'm trying to find who authenticated it, and if they are still around so I can check its authenticity if possible.