David, Glock doesn't assign the 43X a gen but it has more similarities to the gen 5 then other gens like no grip finger grooves, Glocks marksman barrel, ndlc finish, and some internal parts. Hope this helps.

David, the G43X is considered it's own profile - Slimline. It bears more resemblance to Gen 5 but Gen 5 parts will not fit. G43X has many features of the Gen 5 model, except the ambidextrous Slide Stop Lever. Those "Gen 5" like features include the new firing pin block, trigger spring, coil spring on the Slide Stop Lever, coil spring for Slide Lock and the GMB, as well as the front serrations on the slides.
Stay safe & have a great day!

Hi David and welcome. Yes Sir. The frame incorporates elements of the Gen5 and Slimline series such as the short trigger distance, a frame with a built-in beavertail, a reversible magazine catch and the incredibly accurate, match-grade GLOCK Marksman Barrel (GMB) and precision-milled front serrations. Cheers and stay safe!