It will be a cab and trailer.
Motormaster himself will be the cab.
The Trailer becomes the frame for all the components to attach and combine.
The cars making the arms clip on while the legs are hollow rectangles for the cars to slide into, filling out the holes.
The trailer also becomes a base/turret for Motormaster to use when not combined. This is an homage to the G1 toy where Motormaster himself became a base.
The result will be less clean/smooth than the G1 character model of Menasor even though the look is overall similar.