Huh, I guess you learn something new every day! My bad!
I guess I always just misunderstood exactly what the trussrod changes were from the 4001 to the 4003. Is it fair to say that the 4001 basses still had more neck bow issues than the 4003 basses that came later, or is that literally just an issue of, "People didn't know what they were doing when they adjusted them, but then they learned?" I've just never heard of a truss/neck issue on a 4003, whereas I've seen/read about tons of 4001 neck issues. Maybe it's just anecdotal evidence and confirmation bias... like I said, I'm a total idiot when it comes to setup and such.
And yeah, I figured that most of the basses from the 4003 onward used the updated design tweaks. I just didn't know about the McCartney and Squire signatures. If I recall correctly, one of the other big changes on the 4003 was the removal of the bridge pickup cap; later, that cap was added back in with the push/pull pot that they labeled the Vintage Tone Switch(?).