Greg, There is one generation of the model G43. It was the kickoff of most of the Gen 4 features. Holster cut on front of slide, dual captured recoil spring, no finger grooves, tent shaped striker block instead of cylinder shape. That is where Gen 4 models started.

its most like a Gen 4 in the packaging and features

Greg, The Glock 43 Gen 4 is a 6 round, 9mm slimline subcompact pistol that was introduced in mid 2015.

From my understanding there is only one "Gen" Glock 43. It hasn't been out very long. Now there is also the Glock 43x but it is a different format.