At a glance
What can fail
Some 2020 F-350 trucks with 7.3L gas engines and ambulance packages were built with narrower base rear axles instead of the wider axles ordered. The inner tires on the dual rear wheels may rub against the vehicle body.
What the fix does
Dealers will rebuild the rear axle to the wider specification. For unbuilt vehicles, body builders can accept the base axle with a different body design or rebuild the axle to the wider specification, both free of charge.