Yes, you are correct, but it's an 8 digit number (00232277), which doesn't help anything with this odd Thunderbird, other than "00" prefix =1976 and "06" = 1977 on some/all(?) Gibsons.... Then again, Gibson.... Given the number it was either made in 1976 or 2002! I think mine was made and stamped correctly as a 1976, but there was flaw (does have an odd nut and dark dot that could be considered a small blemish in the fretboard grain), and not finished until early 1977. Seems to be the consensus from a few Gibson-knowledgable people anyway. But then again....With 76-79 there's a lot of opportunity for confusion when it comes to s/n. Production was slow to get going in '76, I think some were made in Nashville before Kalamazoo. All '76s and some '77s have decaled s/n, production shifted entirely to Kalamazoo in '77 and Gibson went to stamping the s/n into the back of the headstock. The '76 PG got used well into '77, there were consistency problems with the pickups as well as Scott has noted - I had similar problems with my green '76 as I was restoring it, the first one I found to replace it's missing bridge pickup was totally anemic, the second much better.
IIRC Donnie's white '76 has a stamped 5 digit s/n, again Gibson doesn't make it easy!
The white '76 on Reverb was one that didn't seem to be from 1976 that I mentioned. The stamped S/N didn't seem right either. No "00" prefix.
. & man, you play with some heavy gauges, I've done 110, & that felt too much for me after a while. So i've stuck with 105, never looked back.