I checked my notes and while I can't comment on the H-68 shown on the bulb, mine did have the stamp of 3-8 on the low beams and 5-8 on the high beams. I thought I had looked up the date code guides and wrote them down as March '68 and May '68 which do fit in with my car's build date in May. I suppose they could have made a bunch of lights on March 8 (mine), April 8 (elsewhere in thread), and May 8 (mine) but I think the Month/Year makes more sense. I can pull a headlight to see if it has the H-68 as well but the car is up on the lift right now. I have a photo of the back but the lettering detail is not that clear...