I agree, fbp. Like many manufacturers, their bodies were produced in separate facilities, some owned by the manufacturer, some owned by a contractor.
Hudsons, I believe, were wholly produced in Detroit... judging by the single axle, trunk lid flapping in the breeze and considerable "bow" in the trailer's frame, I'd think the two facilities were quite close to each other...
Looked odd. They all looked new, looked already different colors so I didn't figure heading to be painted. Didn't think about separate plants for body.