romore wrote:
Also check the parking brake cable, it could be frozen. The individual wheel cables are not difficult to replace but you will need to remove the wheel and drum. If the rotor is damaged it is complete tear down time.
Not on E450. The 2006 year has a transmission-mounted parking brake that works on the driveshaft. The rear brakes are disc, and don't incorporate a parking brake. In 2008, Ford went to "Drum In Hat" parking brakes. There's a drum built into the rear discs, so the rear brakes now have Calipers and Pads for Service Brakes PLUS little cable-operated Parking Brakes.
For the OP - Lack of use is the culprit here. As delivery trucks, rental trucks, airport limousines etc. these brakes do fine. Standing a month or more between runs, things get sticky.