Chevy, GMC, Cadillac Radio Antenna Works With 1999-2006 Trucks & SUVs 6mm Base Works With All GMC, Chevy, & Cadillac Trucks & SUVs From 1999-2006 Including Silverado, Escalade, Sierra, and Many More! screws on to your trucks existing base, and start listening to your radio instantly! 6mm Base--30 1/2" Premium Quality Product