I'm not sure on that Stephen, mine has drivers in both holes, one is a dome tweet, the other maybe about a 2" cone driver on a four pin plug, all original. Maybe there is an upgrade to the upgrade, dunno.. But I had mine disassembled to fix up the rust and oxidation on the grilles. A handy tip : Stove black works really well on them, its thin enough to wick into the fine mesh without clogging it, andthe finish once dry looks original..The doorcard on a zed 3 has 2x holes for tweeters 1 should have a tweeter fitted and the larger one will be empty.
That is unless you have the factory upgrade sound system then will be other way round but either way you will still only be using 1 of the speaker spaces in the upper door card.
Stephen.