FOR 73-87 Chevy C10 Behind Seat Cab Corner Speaker Bracket Square body 6×9 steel | eBay
Amazon.com: LOSTAR Pair(2) Speaker Kick Panels for 1981-1987 Che-v-y GMC Pickup Truck Blazer Suburban Interior Front Side : Automotive
Classic Cars — Sound Decision
Amazon.com: ECOTRIC Behind Seat Speaker Brackets Square Body Replacement Compatible with 1973-1987 Chevy/GMC C10 Single Cab or Crew Cap Pickup for 6x9 Speakers : Automotive