There's a lot of differences between Pz38t and Marders, and let's not even speak of Hetzer (widened hull)...
But, there are particular variants of these vehicles, that would not only by feasible to squeeze into one box, but also be varying in purpose they served.
I'm speaking of Marder III M, FlakPanzer 38t Gepard, and Grille ausf. M.
All three would use the same lower hull and suspension, only dffering in superstructure and armament.
I'm not saying that these were almost identical, they were in fact not. But if we want a kit with more than one variant of Pz38t chassis in it, then this is the way to go, these were very similar to each other.