the later frame is about 2" longer, but that's in front of the rad - the 5-7 front fenders w/ matching inners, will fit the 58 cab and rad support, but you'd also have to use the front grille surround and 5-7 hood [8/9 hood slightly narrower at front] - which is to say you can put the whole 5-7 front clip on a 58/9 cab/frame, but you'd hafta fiddle the 4 holes in the hood hinges to match the slightly different mounting location on the later cab, and cut a bit off the frame front or have a bumper that sits out too far
here\'s my Frankentruck , 56 cab, 57 front, 58 frame
Bill