What makes our trucks a 5/4 ton?

Is it the rear end axle, the rear end gears, the tranny, the shafts? Is it the combination of all that?

For example, if you put Rockwells under it, but keep the drive shafts, the 200, the stock motor and tranny- then is it a 2.5 ton? Likewise if you keep the stock axles but swap in a 2.5 ton drivetrain then is it that rating?

I was just curious.
-B.

I've always though it was axle rating with frame and spring size taken into consideration. ?? But then again...yokes on 2.5 ton trucks are MASSIVE compared to our trucks.

Yepper Spicer...
They look at spring capacity, axle capacity, frame strength, and base it on that....the stuff that has to support the weight...the stuff that is needed to move the weight, like tranny and gears, etc. are then matched to the basic weight carrying platform.
brute4c