I am trying to find out what year my Gibson Les Paul guitar is, I have gone to 3 different places to have it appraised and nobody locally can tell me what year I have. It is a Les Paul Custom "Black Beauty" There is no "Made in USA" stamp on the back of the neck, which indicates pre-70. However, there is a volute on the neck, which apparently started in 1970. The serial number, 917911, indicates a year of 1968. There is no indication that the neck has been changed, all the appraisers agree on this fact. Any help or insight with this is appreciated.