The 67/68 differs greatly from the 69 setup. You can use the 67/68 baseplate on the 69, but the 67/68 upper pan won't work on the 69. The 67/68 upper pan was shaped like a pentagon (5 sides). At the peak of that pentagon was a bolt hole. The underhood bracing on the 69 Firebird hood has no provision for that bolt. In fact, that portion of the bracing is scalloped away completely on the 69 hood.

The 69 underhood bracing change was for safety reasons to allow the hood to crumple in the event of a front end collision. The upper pan for the 69 Bird had the same pentagon shape, but at the peak of that pentagon, it was scalloped out, and used two bolts instead of 1.