[GMC Guy]

These are pictures of the two factory 4x10 speaker brackets used to mount the speaker under the dash. Left is a factory speaker bracket for 1960-63 GMC cabs which is offset for the rubber tab to sit on top of the ashtray housing. Right is the factory speaker bracket for 1964-66 cabs. The dash location of the ashtray, heater controls and such was changed between '63 and '64 necessitating the change in the bracket. You can likely fabricate one.









These bolt to the factory under dash bracket above the windshield wiper motor, cradle the speaker around the magnet while the other end wedges on top of the ashtray housing. You really cannot install the speaker and bracket with the radio already in the dash.