This may sound stupid but what exactally does the term 1/2 ton, 3/4 ton, etc. mean or did it come from. Is it the payload they can hold in the bed or rating of the axle or what. Just curious.

Outdated terms to say the least.

When truck first rated they were rated on the weight the could have loaded on to them

a half ton could hold 1000#'s
a 3/4 ton could hold 1500#'s
a 1 ton could hold 2000#'s

At least that is what I was told long time ago.
Funny now a "1/2 ton" has a 1800# or so payload.

I believe that originally it was a rough rating of what the truck could carry in the bed, with a full cab. Accordingly the capacity of my '70 C-10 was about 1500# (500# for the seats and 1,000# in the bed. Emissions regs in the late 70s exemted trucks with GVWR over about 6,000#, so the heavy halfs became common. GVWR on the '70 was, I'm not kidding, 5,000#. This put upward pressure on the 3/4 tons, which previously had grossed about 6400-6700# (those are the ratings from my '74 C2500 and 78 C-20). The next round of GVWR inflation came when the regs capped at 8500#. I think Dodge was first with the 8600GVWR Cummins Ram, but Ford and GM both soon had heavy duty 3/4 tons rated at 8600 GVWR. Now it has become a marketing competition to show the heaviest payload in each class, so we end up with the absurdly named 1500HD with 8600# GVWR.

Generally (and there are exceptions that I won't mention, so don't shoot me!)
at present these guidelines apply:
"1/2 Ton" means GVWR less than 7,000#, 5 or 6 lug wheels, semifloater rear axle. The "lightest" available full sized trucks.

"3/4 Ton" means GVWR between 8600# and 9200#. 8 lug wheels. Full-floater rear axle. Most components are interchangable between 3/4 ton and 1-ton trucks.

1-ton means Dual Rear Wheels and GVWR over 10,000# (SRW 1-ton has single rear wheels and GVWR right around 10,000#)

As of this year Ford is marketing F-450 Pickups, I don't know if this will be called "Class 4" (I hope) or "Ton & 1/4" if brands D, and G decide to compete.

personally I don't find myself using the "ton rating" much anymore. I just call it a "1500" Interestingly my '96 will carry right about 1500# in the bed with a cab full of people and stay within it's rated weight. My 2002 2500HD would carry 2500# in the bed with 750# in the cab . . . I may be on to something (or I may just be on something!)

My 82 C10 has a GVWR or 4900. I've pulled a 35' GN trailer with it... the 250 6 cyl didn't like it, still going, son drives it. 242000 when I replaced engine, still ran fine but was pushing the integrated head, still had original clutch in it,with hardly any wear on it.

yeah years ago it was based on the box's payload capacity. its just a number big deal. just like towing capacity nowadays, what the dealer says is the limit and what i say are the limit are two very different numbers. to me the limit is a trailer i need to be in 4 low for to get rolling from a dead stop in a dually which is a buddies dads bale trailer that holds 30 hay bales all about a thousand pounds apiece. and my truck turns over 500 ponies at the wheels. like i said its just a guideline really.