It appears you are missing the spacers. Look at Hank's photo, you are missing the spacer between the backing plate and the kingpin.
SWEET Sergeant At Arms: Old Dominion Stovebolt Society BUNS?!?!?!Where we're going, we don't need no buns..... 1950 GMC 450 1951 Chevy 1/2-Ton The GreenMachine In the Stovebolt Gallery