this tag doesn't give you the info the door tag gives you.
this was used during the production before the body was painted to give the assy line some basic info about the car.
this below is from Kevin Marti's site about the buck tag
The Buck Tag (AKA Body Tag, Build Tag) were used by the Body and Paint line to prepare the vehicle for completion
(Bucked (Buck Date) This is the date the first piece of sheet metal was welded to another piece of sheet metal to begin forming the buck (if you imagine unbolting everything possible from your vehicle, that which remains is the buck. Generally, on this date, the entire body is produced, appropriate holes are punched, and the body is primed and painted)
The Vehicle Certification Label (or VCL) is the plastic decal, located on the left hand door, that displays a car's serial number, plus encoded data about its features & equipment