Have an 06 F350 crew cab with long bed. Over the top of the spring leaves are buimper things. One has gone completely and the other is almost dead. They are dirty yellow in color. Not sure what these are called but I get a clunk when the leaf spring contacts the frame on the side where the one is gone. Anybody know what these things are called so I can buy some new ones and install? I have to look at the cab frame bumpers as well as they are likely shot; just haven't had a chance. Why Ford ever used such crappy material for those things is beyond me.