The P-51A's sent to India and Burma retained their SCR-274-N HF radios because it enabled them to communicate with the ground troops for CAS. The RAF aircraft in the area had converted to the SCR-522 and thus had to rely on the pilots being properly briefed before setting out on a ground support mission. In fact an additional transmitter was shipped with the P-51A's to ensure that coverage could be used.
P-51B/C aircraft sent to China had radio direction finding equipment installed along with a reduced SCR-274-N installation. Someone did a superb restoration of a China based P-51B a few years back and if I can find my pictures of that I will attach them.
The aircraft in the US that had SCR-522 VHF installed generally had the BC-1206 LF receiver installed so they could receive instructions on standard LF control tower frequencies as well as use the AN Adcock navigational stations. I have four BC-1206 receivers; they were also known as "Detrolas" because that was a major manufacturer of the equipment but not the only one.
A mystery to me is what the fighters used that homed in on their airfields used in the ETO. You find references to that in pilot's personal accounts but it seems that most if not all of the fighters lacked the long wire antenna.
Postwar the BC-1206 disappeared as VHF took over communications but some P-51's and other aircraft had the BC-453 set from the SCR-274-N installation installed instead.