Did a little research on this issue and it looks more like the "short" welding with the plate 1.Pic (TAKOM) seems to be the initial production phase of the turret.
The Dutch and Belgian ones look the same and these where produced more or less at the same time as the German Gepards initially.
The MENG kit with the longer weld seam seems to be the result of an "optimization" process during the production .... makes sense from an engineering view point to reduce complex shapes and less welds etc.
To assist my assumption I believe the simplified attachment receiving the "Nebelwurfanlage" eliminating the original "Plate" would be a logical move.
I have not found any info if something/unit/device was originally "hidden" behind the plate which could also be more easily relocated to simplify the production.
Also no info to what time-line/period this change took place.
Would be interesting if any Dutch or Belgian readers would know if they also had this "mix" on their Cheetah's.
Cheers
Christopher