This isn't really too much of a modification rather than stumbling upon something that works. The tank barrel pops off and fits on the cannons. [In] the 2nd photo down from the top: You have to slightly shave down the sides of the little mini cannon so it stays flush. The triangular shape makes it want to pop off as you can see. [In] the 3rd photo down, the sight/tab on the cannon fits inside the hole on one side or the other of the barrel quite securely. Now Guzzle has something of a tank/gun/sniper/rifle!