I'm about to take over my Grandfathers mint condition Glock 19 originally purchased in the late 80's threw early 90's. I haven't seen it in like 5 years but i believe its in the old tupperware box and does not have a accessory rail. My uncle claims it seems like it's one of the first 400 and the serial number has no alphabetical prefix. Just three zeros like "000396" . All of the serial number list i have seen started with letters like AA or ABC.