Hi Gang,
I recently purchased and installed a Custom Auto Sound USA66 in our 1966 Mustang.
The radio picks up a LOT of stations, but is somewhat hard to tune to a certain station. Back in my USAF electronics days, it was refered to as good sensitivity, but not so good selectivity.
I also use it with my XM radio, and that sounds excellent.
My mistake in installation was not refering to a Mustang wiring diagram. I found what I thought was a good ground with my ohmmeter, when in fact I was reading thru the instrument lamps to ground! That will blow the fuse for the instrument lights real quick! Don't use the blue/red wire for ground, its the instrument panel lights!
I did buy a new front speaker, one with 2 small speakers in the same space as the old 1 speaker. You really can't tell left from right using the front speaker alone, since they are so close together. But with a convertible I don't need a good radio, just one that's loud!
Have fun! Dave