There is no real guarantee on a wrapped box, other than that in that persons opinion, the packs in that box do not show signs of being tampered with. Back in the 80’s, there were ads pretty much every year offering ‘rack pack secrets’ ‘cello codes’, etc, that would allow you to figure out ‘if I can see Steve Sax, the next three cards should be Tom Niedenfeuer, Toby Harrah, and Don Mattingly’ No one can tell for sure that a Mattingly pack wasn’t removed and replaced with another, slightly less popular pack, but they can usually spot if the pack itself has been tampered with to remove a Mattingly.

Howdy — can you clarify what you mean by key dates? Are you looking for hobby milestones (like Fleer getting a baseball license in 1981) or big-name, big-dollar rookie cards (like 1979-80 Topps/OPC Wayne Gretzky)? There won’t be many guarantees about packs being untampered, but you can hedge your bets by getting a look at them (or pics) and buying from reputable sources — BBCE, and probably others, do re-wrap the actual boxes they authenticate and sell, and I *think* they come with some sort of guarantee. You’d have to contact them for details about what’s covered, though.