Brake Auto Adjusters

Hi all, I can across a 8 3/4 rear end that I'm going to put in under my 71' Demon. The measurements suggests it a rear end out of 68' to 70' B body. I believe it has 11" brakes. The brake don't have auto adjusters. I thought someone didn't know what they were doing when they did a brake job, and left parts out. I have since found out that they didn't use auto adjusters in taxis. Is that true? If so why? Can they be swap over to auto adjusters? If you can where can I get the parts that I need? Thanks for you help