There are four different hitch sizes, called categories. The higher category hitches have sturdier lift arms and larger connector pins. There is some flexibility in the tractor hp at which one category hitch ends and the next begins.
| Category | Tractor HP | Top Link Pin Diameter | Lift Arm Pin Diameter |
|---|---|---|---|
| 0 | Up to 20 | 5/8 in | 5/8 in |
| 1 | 20 to 45-55 | 3/4 in | 7/8 in |
| 2 | 45-55 to 90-95 | 1 in | 1⅛ in |
| 3 | 90-95 and up | 1¼ in | 1 7/16 in |