Quote Originally Posted by thunder550 View Post
Get a sheet of 1/2" MDF, cut to size of the back wall, and mount using strips of industrial strength velcro. No holes through the back wall this way. I did it on my truck and it held up great for 6 years.
Tried that in my 69 and the glue on the back of the velcro kept melting in the summer heat. Make sure you get the good stuff.