My recollection is that my 1973 K/20 had a GVW of 7500 pounds but that was based on the 8 ply tires. It would have been 8500 GVW with 10 ply tires and everything else the same.
I
think it weighed somewhere between 4000 and 4500 pounds empty, so the payload would have been 3000 to 4000 pounds depending on tires. So that just goes to show that "three quarter ton" or "one ton" doesn't correspond to actual payload.
Not to mention, of course - that I hauled a
lot more than that on occasion
I did discover that 8 ply tires will blow out with too much weight at too high a speed. Drive slow and you can get away with a lot of overloading.