I have a plant 750 coach....AKA known as a 2019 thor Hurricane 29M... it doesn't have a BIRD... or a trombone, and like "Halfprice" mine has the BIN 225..it is located right behind the batterys between the batterys and the frame..
while on shore power, the converter charges the house batterys, and the chassis through the BIN..
on mine, while having problems symptom's...at the monitor panel voltage would show 13-13.1 volts at the coach.... and 12.0-12.1 on the chassis,... knowing that that is less than full charge, 12.o volts is about 50% of full charge....and 13.0 is maybe 65 or 70%,,,,, just guessing at those numbers