First of all only Vintage MBW's willtake gen Inserts without Mods...
Maybe the new Z series Sub wil accept the Insert,but I don't know because i know the watch only from the Pics...
You can manage to fit a gern Insert on a MBW or TW Sub by grinding down the Bezel with a lathe...
I have done it on mine and now a Gen insert will snap in like the real Deal..
Look here
But this is an old MBW with different case,you can see on the cylindrical Rehaut and Lugholes...
By the way can you post some pics of the Z-Series MBW containing Crystal construction and Bezeconstruction?
Hope this helps