Title says it all lol. I have owned this particular car for 5 years, and I installed a stereo a week ago lol. Put in a custom autosound USA-630, Kenwood dual speaker setup that was initially meant for a 68-69 b-body instead of my 74, but some cutting on the mounting plate and I got it to fit (if I had to do it all over again I would probably make a new mounting plate for it instead of altering the old one), and I have (2) undercover II speaker boxes underneath the seats. Took 2 days to get it all figured and setup properly (I wanted it to look like it was stock, with modern sound). Sound has been great so far, not as high quality as some of the very expensive systems in high class modern cars, but it certainly performs as well as most modern day cars, and probably better than most.
Just wanted to share the excitement! And tell you guys not to give up, for those of you having problems keep in mind it took me about 14 hours to do all this and get it perfect. And perfection craves time lol.