Would you happen to be talking about hitches on the back of your truck for towing a trailer???
Hitch, Receiver Hitch, Trailer Hitch A Receiver Hitch is the primary device that is attached to the rear of the vehicle that allows you to tow. There are six classes of hitches. It is very important to choose the correct class of receiver hitch. Gross trailer weight and tongue weight will determine the hitch that is needed. Do not exceed the lowest rating of any component of your towing system.
GTW = gross trailer weight
WD = weight distrubuting hitch • Class 1 - 1000 to 2500 GTW • Class 2 - 3500 GTW • Class 2.5 - 4,000 GTW • Class 3 - 10,000 WD/6,000 GTW • Class 4 - 12,000 WD/8,000 GTW • Class 5 - 14,000 WD/10,000 GTW