It’s not precisely 3rd party; those set of rules I linked too were sanctioned by the game designer himself (Larry Harris) and is used in many official tournaments.
The basic changes to the box rules are these:
1. There is now a total combined bombing limit per turn that is the territory value. The box rules wording makes it a bombing limit per bomber, which was stupid since it allowed you, if you had enough bombers, to bomb someone’s economy all the way to zero.
2. Techs now apply at the end of your turn, not immediately. Besides the lameness of a turn one long range aircraft sea lion, the designer didn’t like the sneak attack feel of techs.
3. Heavy bombers are no longer so good. You roll two but pick the better of the two rolls, so you can only inflict a maximum of 1 casualty instead of 2. For SBRs, you pick the better of the two and add 1 to it for IPC damage.
4. Super submarines are slightly improved. It raises the defense of subs to 3 as well as the attack.
5. AA guns no longer fire at planes moving during the noncombat phase.
And of course the typo corrections like saying “lesser” instead of “greater” of the two for bombing, etc.