Hello, I hope some here can help me verify what year this P neck is. It's supposed to be a 77 Fretless Maple neck. According to the S/N on the headstock it's a 77-78, and not sure if there is a way to narrow it down further by looking at the heel stamp. Also... what is that white plastic ball-looking thing in the truss rod nut? I'm not sure I can read the number properly, but it looks like 322305 maybe? Thanks for the help!