Yes I have had one for about 6 years in a 69 convertible. I have the Secretaudio SST 200 watt 45X50 system. I installed a dual voice cone speaker in the front dash. I have the two underseat speakers but they will not fit under the front seats so they are on the floor in the back. I pulled out the ash tray and installed the controller over the opening using the ash tray bracket holes. Fit rather nicely. The stereo is hung under the dash over the steering column. Plenty of sound even at highway speeds. (Note I have a fairly quiet exhaust system. ) If I was doing it over I would put in new kick plate speakers and skip the underseat speakers.
Had one for 14 years with no problems other than it's battery drain 24/7. (The original clock does that anyway so I use a battery cut-off when the car sits. I secured it with industrial strength Velcro to the upper dash above the glove box then and have not touched it since. I only have a dual/stereo speaker in the normal dash location so the stereo effect is minimal to non-existent. It does get me AM/FM and leaves my original AM in place in the dash. I put the control in the console box.
