i can't ever recall seeing a code stamped on the box itself which can be used toidentify the box
sometimes, the n/a box has a black cap on the end ,,,,while the gt box tends to have a cap which is the same color as the box itself
the only real way to know may be to break the box and check
or
IF u knew the owner of the donor car the box came from and u KNOW this is the original box it came with (that's a pretty far stretch there though
)