Locking Fuel Cap
You don't seem able to get a locking cap for the old Iveco tanks with an outside screw thread. So after having fuel siphoned out I built my own lock:                         The plates are stainless steel and are glued in place. I tried with a jubilee clip on the cap but it was not secure and the cap leaked a bit because it must have been distorted.  I bought two more matched weatherproof keyed alike padlocks from nothing but .. .    Not very secure?  True but I'd rather the cap was ripped off or unscrewed than the hoses cut or the tank punctured. I am quit vulnerable to a determined thief.