There should be an index point that centers the springs when installing them. You have more problems than that, however.
C-20's of that era have a dual rate spring, the normal ride is on the the middle coils which are "softer". With a load the center coils collapse together and the truck rides on the stiffer coils. Almost all of yours seem to be nearly collapsed with out any load on it.
Not unusual for an older truck that was well used.
Fred
