The suspension parts are redily available, some of them were even used up into the '80s. 1/2 ton and 3/4 share some parts, but there are plenty of series specific parts, too.
For a '65 C20, here's the Moog numbers
Upper Balljoints K680
Lower Balljoints K6025
Upper Control Arm Shaft Kit K6135 or K6256 (offset shaft for additional camber adjustment)
Tie Rod Ends Right Side ES358L (outer) ES358R (inner)
Tie Rod Ends Left Side ES358R (outer) ES358L (inner)
Tie Rod Sleeve ES350S
