If I'm understanding you right, it sounds like they were definately added by one of the previous owners, or maybe, if you were lucky, it could have been a special Dealer type thing. Then only stripes that were offered for the Fist Gen birds were the H.O. stripes on the side along the ridge of the doors and only from wheel well opening to wheel well opening in 67/68, and the T/A stripes over the hood and trunk in 69?

This will take some investigation on your part. You say the cowel tag is missing? Try Pontiac Historical Services with the Vin, and they could give you as much information as anyone on what your car was orderd with from the factory for about $35. http://www.phs-online.com/

Good luck, I hope you find some answres?

Brett - 67 Drop Top 455!