When you owned GM ½ ton in the early years and occasionally need to carry a load above the manufactures suggested limits, over-load rear springs were the answer. They were GM installed or aftermarket.
When installed they were not part of the rear suspension until the stock springs were overloaded. When the bed lowered due to additional weight, the auxiliary springs were contacted and helped support the extra pounds. With rear leaf springs, the different over-load springs companies made them all on the same principal.
A big change was required in this ½ ton over-load system in 1960. A totally different ½ ton now had rear coil springs as standard equipment. A redesigned ½ ton over-load system was now needed.
We recently found this complete revised system attached to a 1960-62 ½ ton. How unusual!
Because the ½ ton differential is the same on 1955-62 and only the new 1960-62 has coil springs, a very unusual overload system was created. The following photos show a used system still attached to a 1960-62 differential. It was such an eye catcher in comparison to the leaf spring system we had to take these digital photos.
Note: It is assumed it will not attach correctly to the 1963-66 as this uses a different differential with their coil rear springs.
Upside down in truck. Thus reversed camera photo.
Unique “wrap around” Differential System.