Most stations in urban areas transmit HD radio now, I understand. If you see the song info on a newer car's radio (post ~2002), it is HD. If a station doesn't transmit HD, the tuner picks up the regular transmission. The main complaint I read was that the radio sometimes switches between the two, but that was the station's fault, which is probably fixed since those reviews were >5 yrs ago.
My 65 Dart has a very small trapezoidal opening for the radio, with two knob holes. Not much would fit thru the hole and I don't plan to hack my dash up. The HD radio panel is only ~1/8" thick so should install on the front of the dash without looking clunky. If the Crutchfield or any of the "secret radios" work, go for it, but too big bucks for me. My 65 Newport had a later Audiovox digital radio installed when I bought it. That was one of the last regular after-market ones with knobs (~1989), but wouldn't fit my Dart.
Before I found the HD tuners, I was thinking of using a motorcyle or boat radio and hiding it, with my bulky factory radio installed just to complete the dash. Those cost ~$40 on ebay. They say that HD makes AM sound like FM and FM sound as good as a CD, but haven't tried it yet.
