From the cowl back, '55-'59 are more or less identical body-wise ('57-'59 have a shorter steering column and the 3200/3600 have a 6" longer bed). Up front, as far as the '55-'57 is conserned, it's mainly trim and grille differences. The '55/'56 use the same grille, hood emblem is different (inverted in shape), the fender emblems are similar, but the '55 is 1 peice mounted below the body crease, the '56 is 2 peice and mounted above the crease. '57 uses the double trapezoid grille, same hood emblem as '56, and a somewhat oval shaped fender emblem, mounted in the same location as '56. '57 is also the only year that the Cameo has it's own side emblem stating "3124" instead of "3100". Another change is the steering column and wheel. The '57 has a dished wheel (used for '58 and '59 also), and has a shorter column as a result. The hubcaps are different, too, and the full passenger car wheelcovers are no longer used on the DeLuxe trucks.
Here's a pic of my '55 3200 (3100 similar)
http://rides.webshots.com/photo/2556194070092261295LXjVTH
