Aren't the CRTs in the 5000-series ceramic neck with a plate glass face? The CRT may well have been replaced after something unfortunate happened to the original one.
I'm really jealous about the blue phosphor screen, that or the green/orange phosphor is something that's on my collection list. I'm still kicking myself that I missed out on a 485 with a P11 phosphor CRT. That would have checked two boxes at once, and it would have been a joy forever.
-- Jeff Dutky