@Grit dog,
My '74 had a guard on it from the factory. It was that hard rubbery kind of plastic. Except it wasn't just in front of the tank, on the pass. side, it curved around the whole front of the tank. I decided one day to see if I could wash out from behind it. Oh yeah, it washed out alright. I saw all this rust after it was clean so I took it out, which turned out to be a lot more involved than I first thought it would be.
Once it was out I saw how bad it was, it was crusted with rust. So like a noob I decided to run a wire brush over the crust. MAN!!! I was grabbing every kind of container I could find! The gas was gushing out from a ton holes big and small that were behind the shield. Thank God it only had less than a 1/4 tank in it. I had dirty dishes I grabbed from the kitchen sink, plastic cups, even the wash tub from the sink, everything. My oil change plastic tubs were all out in my shop which was to far away to run right then. The door from the carport where I was parked was right there at the kitchen. It was kinda funny afterwards.