If you ever pull the neck it would be interesting to see the dates. My September ‘80 is in the B001300’s. …curious how fast they were making them in ‘81?
Our 1980 1Ks are similarly stamped. Mine is 1100-something. It is a November bass (though parts of it were made earlier).
I have a Feb., 1981 as well, serial number 3000 or so. They had already gone to slotted pole pieces by then.
And I have two late 1981s, with mixed hardware. Their serial numbers are around 7000.
They shipped not many more than about 1,500 basses in 1980, starting in June. Serial numbers for basses did not start at 0. They started at around 500. The rule of thumb is that if you have a serial number below 2000, you probably have a 1980 (though that is certainly not absolute, and there are perhaps a few hundred 1980s that have a serial number over 2000).
However, 1981 saw much higher production, with about 6,000 basses made. So not only was 1980 a half year for production, but they were also making them at twice the pace in 1981. As such, 1980s are significantly more rare than 1981s.
Bass production was lower in 1982, with perhaps 3,000 made: back to the pace of 1980, but with a full year's production time. That seems to have been a more standard pace for them from that point. They must have received major retailer orders of 1981s, causing them to really crank them out that year. Perhaps a result of their mid-year introduction taking some time to hype up retailer demand.
You
still see these early production numbers having an effect on supply, if you closely watch the used market for the early big headstock G&Ls. By far the most commonly found examples are 1981s, with the slotted pole pieces. And 1980s are quite rare. You also frequently see seller's try to hype up the slotted pole pieces, by claiming that they "sound better," and/or are "rare." But in reality, the slotted pole pieces mean that you have by far THE most common variant in terms of pickup poles, by a factor of at least 2 – and having played all the variants, they all sound just like 1Ks to me.
The OP's bass was likely completed in the spring of 1981, and it is one of the first 3,500 or so G&L basses ever made.