There was a change in the ADF equipment. The earlier models would have had the loop antenna either by itself or in a football fairing and it was not Automatic direction finding but .required the loop to be rotated manually. They could not put the loop inside the canopy because the primary mission was very long range escort and the airplanes featured the ability to fold back the seat headrest armor and let the pilot, fold back the rudder pedals, recline and take a snooze.
The full production models, the E, F, G went to the ARN-6, which used a different type antenna, similar to the ones used by the Germans, which was a dome sometimes mistaken for a light by the uninformed and also seen inside the canopy on F-86, F-94 and B-47. The ARN-6 was pretty much the standard USAF ADF and remained in service well into the 1970's.