One of the illustrations (below) from the Master Parts Catalog (MPC) is posted by Harold (above) - the 1951-1955st 1/2 ton spare tire carrier. Presumable, Chevrolet and GMC used the same style wheel carriers in that years.
Below, are both "generations" (3 styles) of wheel carriers (1954 Chevrolet Truck MPC):
left image = 1947-1950 (two styles) right image = 1951-1955st (one style)
Those images might help a little in showing/identifying the different mounting bolt locations?
