To add... there appears to be 2 different shock mounts. One has a square end to accommodate the sway bar. The other slanted. Hole for the shock is in the same location for both. Maybe the diameter of the sway bar off high. Both my 58 and 59 panel trucks have the sway bar and the square end mount. My 58 stepside has the slanted end version. I'm not sure if it came with a factory sway bar or not.
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel