as HotrodLincoln said, it may be best to install a sender unit that has the pickup tube in it with the strainer on it. My external tank on my 58 6400 is NASTY inside. (I just need it to move it around the yard for now and will eventually replace it with something else). It had a small fuel outlet at the bottom, I plugged that and used an extra sender unit I had that I had shortened the pickup tube for my Suburban. It now sucks gas from about 2" above the bottom. True, I can't use all the gas in the tank but for a temp fix so I can move it around the yard while I am getting other stuff done, it works great.
