WB,

There is not an 100% original side-mount tire carrier until 1953.

However, the 1953 side-mount carrier can be easily used on earlier trucks. The drawings in the 47-55 Factory Assembly Manual (1954/55 trucks, actually) that Lonnie refers too are a very good start - the only difference is in the angle of the top of the carrier frame, where it meets the underside of the lip of the bedside.

Tim