Just to clarify, we have already moved on from the topic of which taillights these are. You are correct that they are Not 68s. They are the correct for this car 67s.
It is a simple matter of the 68 decklid, with 68 trim that at some point was used to replace the original 67 decklid on this 67 Barracuda. The OP is now in the process of collecting parts to correctly install the 67 trim.
Appreciate your responses, but it is only going to muddy up the OP.