Why would you ever need to change a brake back plate? In this case, it’s quite simple. When you break all the wheel studs off your rear driver’s side wheel, and the tire tries to pass you at 75mph while you’re in the fast lane passing a semi-truck and towing a trailer, the only piece of the vehicle holding the truck off the road surface is the brake rotor and backing plate; that’s when you’ll need to replace the brake back plate! 
When doing a brake job or removing the wheel/tire for any reason, lug nuts must be tightened to the manufacturer’s specification, or the wheel can come loose. So how did the studs all break on one wheel? I believe the studs and nuts were stressed by over-tightening the wheel lugnuts in a prior tire rotation. I usually request the lugnuts be torqued to the manufacturer’s recommended spec, which is 149 ft/lbs, according to Ford. The tire shop that previously worked on the vehicle, I know, over-torqued the lug nuts because while doing the rear rotors and pads, I had to use an extra-long breaker bar and extension to remove them. The rear rotors had warped after driving some of the canyon roads we find ourselves on. I replaced the rotors and pads, hand-torqued the lugs to 149 ft/lbs, drove 100 miles, and retorqued them, and they seemed loose. After another 3000 miles, the wheel studs snapped, hence my predicament.
After getting the truck towed home, I replaced the rear driver-side rotor, bent the backing plate out to about as normal as possible, and proceeded to test drive. Guess what? The backing plate had to be replaced because no amount of work to straighten the backing plate would stop the emergency brake pads from rubbing. So that’s the story, now onto the proper fix.
Step 1: Order the correct part from Ford (no one else carries the replacement for my application).
Step 2: Get the truck’s wheel, brake rotor, and caliper mount off the axle.
Step 3: Open the rear differential to remove the C-Clip from the driver’s side axle shaft; there is a combination pin and bolt holding the cross pin in the carrier. This must be removed in order to remove the C-Clip.
Step 4: Remove the rear axle carefully. Try not to damage the axle seal. If there is any sign of leakage or damage, replace the seal.
Step 5: Remove the emergency brake shoes, check for damage to the shoes or shoe hardware, and replace if needed.
Step 6: Remove the three bolts holding the baking plate to the axle housing.
Step 7: Replace the backing plate, emergency shoes, and hardware; adjust the shoes using the star wheel to loosen them all the way.
Step 8: Reinstall the rotor and the caliper mounting bracket; make sure the pads are spread wide enough to fit over the rotor.
Step 9: Mount the wheel and tire, torquing to the manufacturer’s specifications.
Step 10: With the transmission in the neutral position, adjust the emergency brake shoes.
Step 11: Pump the brake pedal before starting (do not pump so that the pedal goes all the way to the floor; pump a few times if needed) – the pedal will become stiffer as you pump.
You’re now ready to test drive. Be sure you re-torque those wheel studs after 100 miles.
