The complaint was no four wheel drive, no heater control functionality, and poor braking. This F350 had automatic locking hubs which used a vacuum pulse to engage the hubs. However, the right inner hub bearing had failed causing a vacuum leak so the four wheel drive stopped functioning and the heater controls did not work. I replaced the wheel hub, axle, installed manual locking hubs, re-routed the vacuum hoses, brakes and rotors. Four wheel drive was restored, heaters worked and proper brake function was restored.