I spent 23 years working as a tech in ford dealerships. the new trucks you see on dealer lots with plows will have the full factory warranty. if you buy a truck and add a plow, the plow and associated parts are not warranted through the dealer but the truck still is unless the install of the plow caused the problem ie poor workmanship or plow is to big for the truck. damage from plowing is not warrantable. extended warranties will have disclaimers that they will not cover vehicles with plows unless upgrade the coverage to cover a plow truck.