What's the spacing between the rear cargo area back wall and the gas tank on a 78? Am looking at mounting an amp there and don't need to be dealing with holes drilled into my tank!

TIA

 

not sure exactly how much space you have but when i mounted mine i think i used 1/2" or a little bit longer self tapping screw but make sure you don't mount it too high or the screws will interfer with the pull shade. i just relocated my amp to the jack box behind the passenger seat.