Behind Seat Speaker Brackets for Chevy C10 1973-1987 Squarebody for 6x9 Speakers - AliExpress
Behind Seat Cab Corner Speaker Brackets Square body FOR 73-87 Chevy C10 Sale | eBay
Amazon.com: ENIXWILL Behind Seat Speaker Brackets fit for Chevy C10 1973-1987 Squarebody for 6x9 Speakers : Electronics
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