Buy the house in Dillimore and make sure that the garage is empty. In the mission Tanker Commander mission that you get from Catalina, there is a completely armored Sabre available. Instead of getting in the truck, go turn around and go around the side of the gas station. The Sabre that is used to try to disconnect the trailer is sitting there, locked. You can either push it by running into it or push it with the truck. Push it down the street you are on to your garage and kill Catalina. Then, push it into your garage and let it close. When you go back to it, you will find that it is fireproof, bulletproof, and dent-proof.