Hy Bernd and guys, I could not find a front track specification for the 55-59, but I know the frame of a 55A and older truck is tapered, where the 55-59 frame rails are parallel, so the minimum you would have to do is redrill the "U" bolt holes in the axle. Also the kingpins appear to be different in some way, Carters list a different p/n for the two axles, I would say this is not an easy conversion to do.
