Classic Instruments 1978-88 Chevy G-Body direct-fit package is an all-electric cluster featuring OE style. Hybrid lighting combines original perimeter lighting with added backlighting. Turn signals and high beam indicators are in the original locations and the kit includes new check engine and high beam sockets with LED bulbs. Also includes wiring harness, push-button speedometer calibration, new acrylic lens, a built-in ECM signal filter switch, and Classic Instruments' Zeus Speedometer Technology built-in. No external control boxes are necessary to work directly with ECM or VSS signals. Programmable for any fuel-sending unit, no fuel-sending unit included. All other necessary sending units are included in a Classic Instruments GM sending unit kit. Install using customers' existing diffuser.