Amazon.com: Compatible with 2002-2013 Chevy Avalanche Underseat Alpine Type S S-W12D2 Dual 12" Sub Box Enclosure with S-A60M Amplifier & 4GA Amp Kit : Electronics
EXT 12" Kicker Subwoofers+Enclosure For 02-13 Chevy Avalanche, Cadillac Escalade
02-13 Chevy Avalanche Underseat Harmony A122 Dual 12" Sub Box & HA-A800.1 Amp | eBay
Custom Stereo System 2004 Chevy Avalanche - YouTube