How many movies have David Osterhout and George Armitage collaborated on?

They have worked on 5 movies together! Their first movie together was Gas! -Or- It Became Necessary to Destroy the World in Order to Save It. (1970) while their highest rated movie together was Von Richthofen and Brown (1971). They have not worked together since Fighting Mad (1976). They are most known for their action films together.