I don't know why I didn't check this out sooner, but I was checking a couple of measurements for a guy over on RickResource, and so while I had my instruments out I ran them through the serial number decoder for fun.
My 320 JG: UJ -- October, 1981. October is, of course, the month JL was born.
My 360-12WB FG ckbd: VB -- February, 1982. February is, of course, the month GH was born, and the guitar is younger than the 320, just as GH is younger than JL.
My 4002? No correlation. UL -- December, 1981. But...my birthday is December 8. Really, it is. So that does make the bass between the 320 and the 360-12 in age, just like Macca is younger than JL, but older than GH.
Now, I got each of these instruments at completely different times from different places years apart: the 320 new from a dealer in Texas, the 360-12 in 1989 used traded in to a dealer local to me, and the 4002 in @1993 technically "used" from a dealer now out of business in Denver from his private collection. I had no clue about the serial numbers, and did not plan their purchases in that regard. I wanted the particular models at the particular times, and purchased the first one that came along in good shape to fit the $$ budget I had at the time.
OK, one lucky coincidence would be great. But all this? And it gets better: I used to own a Les Paul Custom that looked a lot like the red-refinished LP Std George & EC used on Abbey Road. It also had a birthday of February or March of 1979, and EC's birthday is in March.
I love coincidences!