1 None of us like to think about it, but the more you drive your classic, the higher the chance you’ll eventually be involved in an accident. The stock Mustang gas tank simply bolts to the trunk floor with self tapping fasteners in the ’65-’70 Mustang. To effectively place it “outside” the car means creating a new trunk floor over the tank. The easiest way to accomplish this is with a bolt-in solution called Tank Armor from Antioch Mustang Stable. Tank Armor is 11-gauge steel and structurally reinforces the rear of the Mustang and protects the passenger compartment from fuel tank rupture.