[ray_mcavoy]

Actually, GM did piggyback off the ignition power supply on some of these trucks to power the ESC (Electronic Spark Control) module. Trucks that originally had ESC will have the regular pink wire feeding power to the HEI. An orange fusible link wire is joined in at the HEI connector. The other end of the orange fusible link splices to a pink wire that goes through a grommet in the firewall along with 6 or 7 other wires that lead to the ESC module mounted up under the dash near the glovebox.