[Botietruck]

Just noticed this thread and and I know I'm late, but I just went through this with my '71. I installed the Custom Autosound stereo & dual voice speaker. My cab did not have the holes drilled for the rear support bracket and I forgot to drill them while everything was out. Now, I did find the 2 factory dimples for the screw holes in the inside cowl area. I purchased an extra long 1/8' drill bit (about 12'-14" long-less than $10.00) at Home Depot and carefully went in through the stereo hole in the dash, and very slowly drilled the holes. It worked like a charm! I did have to tweak the speaker bracket in order to get a good fit around the center a/c duct, but once that was done, everything fit very well. It was not easy getting the dash pad nut back on and tightened, but it just took some time.