The space behind the rear instrument panel severely limits the choices for panel mounted radios that can be installed in the OTW. However, I found a radio that fits beautifully and works very well. It is the Trig TY91. It has flip flop freqs and a built-in intercom. It also has a memory and can be interfaced with certain GPS units. I mounted the transmitter/receiver under the front seat and the control head in the rear instrument panel. Another nice feature is it will accommodate another control head in the front seat panel. This would give control redundancy as well as emergency control should the pilot become unable to operate the radio. Check it out. This is a great radio and it fits!