Off the top of my head, during WWII the following truck-tractors were made:
1 1/2 ton Chevy
5 ton GMC CCW (looks like a CCKW, but non-driven front axle, and on-road use only, hence 5 ton rating)
a tractor variant of the Studebaker US6
a tractor variant of the International M5H6
White 444T 4x4
The Autocar that was identical to the 444T - somethng like a U4144 4x4
A bigger (5-6 ton) Autocar 4x4
Mack built some 4x4 tractors as well.
Then of course there was the Pacific - but it takes a 3 1/2 inch kingpin.
I'm sure there are more, but this is best I can do off the top of my head. And I sure can't remember who made the fifth wheels for each of these. The TM9-2800 MAY associate fifth wheel brands with particular trucks, but I am not sure.
Regards,
David