Hello all. I'm in the process of purchasing a 1986 PRS Custom 24 in blue. The Guitar appears to be a fantastic deal, but the serial number is a little odd. It has the stamped 6, but has a 1900 serial number. Is this common and does it make the guitar an '87 and valued that way? I've been wanting to purchase an actual 86 for quite awhile and want to make sure it's right. Thanks for the help!!