Bruce - the 55-59 factory shop manual has all the info you'll need for all models of truck - tho it won't have numbers of individual components, you'll prolly be able to tell from the pics and details wether the rear is original GM or not - also, GL and Mike are right, that truck should have 19.5's front and rear, or [if actually a 4400], 22.5's front and rear - also there wasn't a 172" WB, the 4100 was 132.5", the 6000 series was 174.5" [all from the manual]
Bill
