1947-59 1/2 ton GM trucks' king pin bushing are floating - no reaming the bushings.
Larger 47-59 GM trucks king pin bushings need to be reamed.
This applies to standard and over-sized bushings.
Of course, if you have to use an over-sized king pin because the king pin is loose in the axle, you will have to drill/ream the holes in the axle to fit the larger diameter of an over-sized king pin (for all sizes of trucks).
