Joe's right, if its a standard truck steering box, the tube is just a rolled sheet metal piece that clamps to the gear box with a small clamp, sorta like a bicycle seat clamp. The tube should just pull off with a little force. The top of the tube holds the upper steering shaft bearing and the horn wire runs down the tube and exits out by the clamp through a small opening.
A military gear my be different, I couldn't tell you anything about them.
Joe
