The " V5 " on a hitch is a SAE rating. It has confused many folks before. It has nothing to do with the load capacity, only that it meets SAE specs for hitches in North America. You will never see a class 5 on a 1/2 ton truck and until recently they had not been on 3/4 ton trucks or SRW 1 tons. Only since the new monsters from Ford and GM have you seen such heavy hitches on a SRW truck.
Class 1 = 2000# and 200# tongue weight
Class 2 = 3500# and 350# tongue weight
Class 3 = 5000# and 500# tongue weight then upto 7500# and 750# with WD
Class 4 = 7500# and 750# tongue weight then upto 10000# and 1000# with WD
Class 5 = 12,000# and 1200# No WD limit usually (I have seen as much as 17,000# and 1,700# limits)
These are just guide lines and some hitches may be more but never less in a certain class.
Also its possible to put a hitch on a truck or SUV that exceeds the vehicles limits. Case in point is my neighbors fathers 1/2 ton Chevy with a 5.3L and 3.42 gears. Its about a 2005 model and its only rated at 7,700# tow rating but has a Class 4 hitch rated at 10,000# with WD. He was trying to convince us it had a 10,000# tow rating.
Chris