I've previously posted about this 1-1/2 - 2ton thing but looks like it's time to do it again. For everyone's information there really is only one way to determine the capacity of a truck chassis and this is by it's GVWR and GAWR. That's GrossVehicle WeightRating and GrossAxleWeightRating. That describes how it was built and what the builder claims/intends as capacity rating. Forget that it is seldom considered when loading a great many trucks.
The terms 1 ton, ton & half and two ton are hold overs from the old days of the 30's - 40's and referred to the capacity rating of the front axle. So if your truck was a "2 ton" it meant the front axle could support the trucks's weight and a load of 2 tons. Now that isn't much but one must absolutely get a 40's mindset going on if this is to make any sense to you. It does to me but I'm older than most here it seems. That allows me to remember the size of delivery/farm trucks from earlier times and relate it to todays chassis. Nowadays the capacities of chassis are considerably higher than from those times.
Example: Wetwilly says his 55' "two-ton" is rated at 18,000 GVWR. Let's see how that compares:
Today that would equate to a F&%d F450-F550 chassis or Navistar TerraStar which has 19'.5 wheels and a low profile as compared to yesteryears trucks which we consider as "real trucks" while newer ones are kind of puny looking.
The best way to make a comparison is to look at the Class rating. Today we have trucks divided into the following classification by GVWR:
Class I 0-6000 lbs
Class II 6001-10000
Class III 10001 - 14000 (F350-GM3500-3500 Ram)
Class IV 14001 - 16000 F450-4500 Ram
Class V 16001 - 19500 (F550-5500 Ram- Isuzu NPR
Class VI 19501 - 26000 F650-F750
Class VII 26001 - 33000
Class VIII 33001 - + (all tandem trucks and heavy single axles)
As stated a great many of todays trucks and the older ones too are overloaded. I've often done it myself and with no repercussions worthy of report so there is little of anything to be learned from the old terminology. So in the future if you want to understand your truck then you may refer to this info and hopefully we can all begin to use the current terminology so that the "what did I buy" questions can be laid to rest. And what you can load/haul will begin to make some sense.
Edit: Dave's info here was made into a helpful Tech Tip. Appreciate the work he put into this! 
