1963-1972 C10 with Coil Spring Rear & Drum Brakes 5 inch Front / 5 inch Rear Complete Lowering Kit with Upper Control Arms
Upper and lower control arms working with a engineered drop springs result in a five inch drop that you can align. Completely assembled, they come with urethane bushings, mounting shafts, and ball joints. The rear uses custom designed coils springs for a five inch drop.
See the bog post here.