Assuming those are the shoe return springs, not sure if they are the same but, I bought some Raybestos H9226 springs off Ebay for my 1958 6400.
http://www.ebay.com/itm/151853414908?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


Mike
1955 Chevy 6400 ex-flatbed (no bed now!) sold September 2023
In the Stovebolt Gallery
1958 Chevy 6400 flatbed W/dump
In the Stovebolt Gallery
1959 Chevy Suburban Owned for almost 20 years, Daily Driver -- sold May 2016
In the Stovebolt Gallery

Sufficient unto the day is the evil thereof