Excellent that you found those stickers. You can get alot of information from playfield stickers or ink stamps that were done at factory, and in most cases, they have never been viewed by anyone unless u point out to an owner that they exsist.
  I am a HUGE fan of studying every inch of a pinball machine (espescially every bit of the playfields side, base and any and everywhere that a sticker or a ink stamp could be placed/hidden). Even tags on wiring harnesses show interesting info as well.

You get to find out -
*playfield number you have out of say a run of 1100 etc. You sometimes find the playfield was produced 4 months before a machine was made, or even only a week before the machine was on the production line.
*You find what machine number you have, example 2453 out of 2500.
*exact date the pinball was made.
*persons name who signed off on machine
*sometimes date produced/made versus date shipped (can show overstock or understock)
*country of destination
*playfield version. prototype vs std, versus updated version with any changes etc

Just a batch of interesting items. Some people wont find it interesting, but it tells a story about the machine. Sort of its hidden DNA/personality.lol so to speak. I found one of my machines was originally delivered to China from the sticker/ink print investigating. (and many other surprises about alot of my other machines).

Look all over your ACDC machines and learn a bit more about your machine. A bit of fun learning some stuff.