Add StreetGRIP rear dual-rate springs to your 1963-1972 C10. The dual-rate design provides the best of both worlds.  The "soft" spring rate section helps your truck to comfortably transition over small road irregularities. As the springs compress further (through large bumps or cornering), they transition to the firmer spring rate to better support the greater loading. StreetGRIP coil springs are CNC cold-wound from high tensile premium steel by then powder-coated for long-lasting, consistent operation. StreetGRIP coil springs are RideTech works closely with Hyperco, our technology partner, to develop custom dual spring rates to ensure the best performance for your classic pickup. Sold as a pair.