The Great Planes F-4 Phantom was all balsa. The OP's model has a molded fuselage, so it cannot be the Great Planes kit. I know that there was an F-4 kit manufactured in the 1970's/1980's that came in a few versions. One was with a 'glass fuselage and either built-up or foam wings (I don't recall which), and the other had fully-molded wings and fuselage. I cannot recall the name of the kit maker. Westcoast RC products, maybe?