Amazon.com: Compatible with GMC Sierra 2500 1999-2002 Rear Door Factory Replacement Harmony HA-R65 Speakers New : Electronics
1999 GMC Sierra 1500 Speaker - ACDelco 15038567
Front Door Speaker Replacement Package for 1999-2000 GMC Sierra Classic | NVX | eBay
JL Audio 1999-2006 Chevrolet Silverado / GMC Sierra Crew Cab Trucks & Early 2007 Crew Cab “Classic” Trucks Subwoofer Stealthbox | Audio Express | Western United States
Dual 6.5" (D6) Speaker Pods for 1995-1999 GMC Sierra - Custom Speaker Pods
Amazon.com: Compatible with Chevy Silverado or GMC Sierra Full Size Extended Cab Truck 1999-2006 Dual 10" Subwoofer Sub Box Speaker Enclosure : Electronics
1999-2002 Chevrolet Silverado and GMC Sierra extended cab
GMC Sierra 1999-2006 Factory Speaker Replacement Harmony R65 R46 Package New - Walmart.com
4x6 Speakers for 1999 2000 2001 2002 2003 2004 2005 2006 2007 GMC Sierra