suspect clutch disc
clicking from rear end on 1997 Ford Expedition
Did you ever find out what was causing this problem?
2 more answers
Check your rear AC unit.
if your vehicle is equipped with rear a/c there might be a problem with the door actuators on the rear a/c there are two to find out witch one change the a/c from cold to hot to see if the sound goes away and do the same with the fan speed. they are easy to replace and cost around $50.