In a large bowl, combine popcorn and nuts; set aside. In a large saucepan, combine the sugar, butter and corn syrup; bring to a boil. Boil for 5 minutes, stirring occasionally. Remove from the heat; add vanilla. Pour over popcorn mixture; stir to coat. Spread onto two greased baking sheets. Bake at 250degrees for 1 hour or until dry, stirring every 15 minutes. Remove from pans to waxed paper to cool. Break into clusters. Store in airtight containers. Yield: about 6-1/2 quarts.