when it comes to rare, I've seen and heard a lot, but I've never seen these

 is specialty-order railroad 1962 Crew Cab pickup truck, 6 were made

https://www.hotcars.com/rarest-american-pickup-trucks-ever-made/#gmc-railroad-crew-cab---6-units

only 17 examples of the peculiar 1991 Ford Skyranger Convertible exist.

https://www.hotcars.com/rarest-american-pickup-trucks-ever-made/#ford-skyranger-convertible---17-units

When the Bigfoot monster truck was big news in the 1980s, it was only prudent for Ford to ride the wave for as far as it would go. The Ford and Bob Chandler partnership resulted in the Bigfoot Cruiser package, equipped in approximately 300 F-250s built from 1987 to 1990.

Most of them were recalled for unsafe after market stuff that made them special.

https://www.hotcars.com/rarest-american-pickup-trucks-ever-made/#ford-f-250-bigfoot-cruiser---300-units