https://www.ebay.com/itm/126589511081Unfortunately, X code body tags have disappeared into the abyss along with Protect-O-Plates and claimed 'original' paperwork. They can no longer be taken at face value. All are available in reproduction. Repro stuff often has errors but takes someone with lots of experience to detect. Yes, I have seen repro Van Nuys tags.
VIN tags have also been reproduced.
There are plenty of real X code body tags out there, salvaged from junked cars years ago. The car in the link has a real 04C [April '69] X77 body tag. Unfortunately, the VIN was final assembled October 1968 meaning one or both tags are not original to the chassis. The hidden VINs should be examined but may also be altered.
Post some pics. Plenty of very knowledgeable folks here happy to give advice.