Welcome, and congrats! And yeah, it can be so frustrating trying to find information on these Japanese vintage Hohners. I've looked for catalogs, but so far nothing with free images available. Here's what I have found so far. The HG310 LE was endorsed by Hank Williams, Jr. in the late 70s. Back then you could hardly open an issue of Guitar Player magazine without seeing Bocephus holding a HG310, just grinning away. The ad was more hype than specs, of course. It referred to the top of the guitar as "close grained white spruce" and the sides & back as "book-matched Rosewood." The ad copy never actually said whether either was solid wood. I'm guessing that the top was solid, but I don't know about the B&S. As for what's on your neck block, I can't say. I don't know common or uncommon it is. all I do know is that the neck block on mine has no such second number. Here's that ad of Hank, Jr. with his Hohner HG310.