The G43x and G48 share the same frame, with a 10rd mag. The G43 has a 6 rd magazine and can't use the 43x/48 10rd mag, and vice versa. But the slides are interchangeable between the 3. Allegedly, Glock has heard the displeasure regarding the silver slides, and is releasing versions with the standard black color.
On an interesting note, I've read a few threads on other forums regarding magazine options for the G43x and G48. With slight modifications, the Mecgar CZ75 compact magazine (15rd capacity) fits. It is a little bit long and doesn't lock the slide back on an empty magazine, but people are exploring options. Apparently, the only modification necessary is to cut a new mag catch. The floor plate is not flush fitting, but I expect that Mecgar might consider making magazines if they perceived a demand. However, I would also suggest a steel mag release if one is made to avoid the steel mag tearing up the polymer mag catch. To be 100% functional, it needs a modified follower so that the slide will lock back. That's a fairly easy engineering task for Mecgar.