I think there are a few real-deal experts on the older guitars on the forum - Glide and Queen City Guitars spring to mind.
It'd be interesting to see what they know / think if they see this thread and want to reply. My comments above are just based on a small sample of early guitars that I've seen / pulled apart. It'd be cool to be corrected if I'm wrong. For example, I've not seen inside any super early guitars (say the first ten off the line) so it'd be interesting to know what's in those - 7 and 8s as a guess, but it is a guess.
Ditto any of the pre-production guitars to the 'modern' design. The few of those where I've seen pictures seem to have blank-back pickups with tape written pickup codes on them (kinda like the stickers with "Gloria" etc on them in very early Fenders). Again it'd be interesting to hear what's in those from anyone who owns one or has pulled one apart. I'm aware the early guitars are a bit of a niche interest on the Forum but post away if you have anything.
Anyway here's the accompanying "7" that's on the VY guitar with an "8" in the bass position. The pickup is also electro-etched "Bridge", which I assume was done before it was stamped.