Hi Anthony.All the upper seat frames were stamped...even the ones built in 1967 for the 68 model year.What the TSB is talking about is all the internal stops and guides etc.Looks like even if your late 68 built car was not equipped with the optional headrests it had all the hardware installed....except for the outside bezels and of course the headrests.Same deal with the 3rd tail light bulb in 69 Coronets.About a month prior to the new bumped tail light lense and 3 bulb housings the new tail lamp harness appeared.