not convinced of that, kook - if you look at those pics more closley yu'll find that the cab being put on the chassis is completely finished, tho' minus the front clip [because the steering col is on frame] - look at the size of back springs - appears most likely a cab/chassis model which will get the different front fenders of more limited production.
and the cab and the panel body being assembled are not on frames but on jigs. ya can't think that all the welding sparks are flyin around on complete, painted chassis that will then be sold?
three lines: chassis assembly; body assembly; final assembly. that's how the cabs were the same basic unit for any size truck.
Bill