Don't understand. Upper/lower plates. They use the holland Brinkley hitch and is probably the best hitch around. When they surround the pin and the lever goes behind the little spring loaded pin, nothing it going to seperate the pin from the hitch. The top part of your hitch may set on the housing. I have a teflon plate between the metal. The two parts of the hitch that surround the pin may leave space but those pieces are 1 1/8 inches thick unlike the cheaper hitchs that are 1/2" Don't worry about it you got the best there is