I don't remember if it's balanced audio or not but I'm pretty sure the audio output can be found on pins 18 and 19 of the DB37 connector on the back of the radio.
Your audio interface should be transformer coupled anyway, just for safety considerations, and as long as there's a transformer between the radio and the distribution input, then the distribution system will see balanced audio even if the radio's output is single ended.
Easy way to tell: Use an ohmmeter and see if either pin 18 or 19 is at ground. If one of those pins is at ground, then it's single ended audio.