Where is the cabin air filter located on Ford super duty f250 6.0 engine?

The cabin air filter on a Ford Super Duty F-250 with a 6.0L engine (and most other years and engines) is located behind the glove box. You'll need to remove or at least significantly lower the glove box to access it. There's usually a few screws or clips holding it in place. Consult your owner's manual for the specific steps, as the exact procedure can vary slightly by year.