The Stovebolt Site Forums The Shop Area Engine Shop how to tell what size my motor is

thanks i am 14 almost 15 and this is my first truck.
my uncle has restored a 56 chevy and a 65 chevy. the 65 had power windows locks everything.
he sold them both i dont know how long ago. (restored them in the 70's) and now has a 65 mustang and a 65 chevy truck mustang for his wife and truck for him.
and his engine for the 65 truck has the triangles on it.