Looking at Gigabytes website there appears to have been two models of this board with numerous revisions each, a "premium" model (7zx) and a "cost cut" model (7zx-1). The differences seem to be audio (creative ct8550), isa slot and dual bios, all of which were omitted on the cost-cut model. However, at revision v5.1 they seemed to drop the aforementioned features on both models and the only difference seems to be in the chipset (KT133A vs KT133).
Interestingly, Gigabyte's web site faq also talks about a -1 label on the corner of the 7zx-1 motherboards but I haven't seen it in any pictures of boards without the audio chip, isa slot and dual bios.
But since those features are all missing or all present on a given board I'm inclined to believe there was some kind of silkscreen labeling error, or maybe it was purposely omitted and only the sticker on the box said 7zx-1, or it possibly varied by market.
I'm also not sure why the difference in FSB that was mentioned above since all revisions of both models until v5.1 used the same chipset, at least according to Gigabyte's website.
I used one of these boards in my first gaming build with a Duron 800 and would like to make a retro rig based on that build. Mine had an isa slot and given the time period I purchased it, it was most likely a 7zx v1.0.