If I were you, I wouldn't ride in or allow your friend to come near my house until he recharges the truck with R134. Although I would never do it, I understand thoroughly the desparation which causes people to use alternative, explosive refrigerants in their originally R12 systems. But this F350 being a few years old uses R134. Why would anyone do this when R134 is only a few bucks a pound?
Please encourage your friend to correct this for the safety of he and his family.