I would recommend that you buy a shop manual from one of the vendors for you truck. They are invaluable in putting things back together.
This is for the rears on a 1966 half ton:
http://www.pbase.com/nufsed/drumbrakeTake away the emergency brake pieces and the self adjuster and it should be pretty close, but I won't swear to it.
some more '66 style manual images:
http://picasaweb.google.com/Woogeroo/1966c10styleebrakes#Get a shop manual, you won't regret it.
I'm guessing you'd need a '55 2nd series and a '58 supplement... or they made a a lot of changes in '58... so you might could get away with only the '58 shop manual.
Maybe someone with more experience with those models will stop in and shed some light on this for us.
-W