in chronological order
SST 2000 : transversal stick pack, then the following year a saddle chassis with 2x3 batt on each side
SST 98 : right side saddle, top plate lowered
SST 99' pro : same layout but a few changes, in fact many little changes
Axis : motor in the center of the car, batteries back
Axis 2 : same layout but " double " bottom plate and ball ended links intead of top plate.
Mission :back to a right sided battery, but 6x1. Otherwise pretty common layout compared to now, except motor behind spur. ( same as yok mr4tc )
It's prety hard to figure the filliation between each generation, they kept and changed many little things until the "from scratch or almost " Mi2, then Mi2 EC.
hope this helps.
Great cars IMHO, they basically were everywhere in EU in the nineties. Far from being as sturdy as nowadays cars, though, don't slap them on the boards too much.
I love wedge bodies. I love dish wheels.