I have been told that there were about 10 RT 524's for every RT246 manufactured.
The RT524 was a general purpose single channel radio and was put in all kinds of vehicles. The RT246 was intended primarily for tracked vehicles where the radio might be located in an area not readily accessed by the crew. In addition to the push buttons there is a remote control box that is about the same size as a VIC-1 crew box that allows selection of any of the 10 presets.
The way the presets are set is by adjusting a pot behind the push button panel. When the radio is set to remote (enabling the push buttons) the frequency selector knob is controlled by a servo motor inside. As you adjust the pot for the push button, the frequency knob will spin to track its position. The resolution is a little low, so you have to be pretty precise in your adjustment (maybe a couple of degrees). If you don't get it just right sometimes the radio will tune dead on and sometimes it will end up stopping .05mhz off of your target frequency. I think more worn radios have a harder time with this.
I like the RT246 better because I like watching it spin and listening to the sound it makes when I push the channel buttons. That's just personal preference though. There is a little bit more to go wrong with them. Most prominent in my mind is the band switch, which is also servo controlled with no manual override. If a wire breaks or the motor takes a dump, you can't switch bands. On the RT524 there is a manual linkage and no servo. I'm not saying I've ever seen one go bad, just that it's an added complexity.
Augi