The hitch pin is a 1/4" diameter and the hose clamps hold the flag to the pole.

 

I know this thread has been dead a while I just wanted to say thanks for the help this worked out great

 

Glad it worked for you! Got any pictures of it on your truck?
I'm gonna have to come up with a new mount myself because I've since put in a bed box and that would make it very hard to mount a flag there. Back to the drawing board for me!

 

When its nicer out ill put them in and take pictures right now its crappy out and I think you can do the same thing for the rear holes as well