It is my understanding that Airstream changed the aluminum sometime during the production year of 1982. Prior to that it can be brought to a mirror shine after that it can not. I polished ours this spring, stripping the clear coat on the front panels only where it was damaged. I was able to get a shine but I did buff it down to match the remainder of the coach. One thing to remember as you start this project is that there are many "things" bolted onto the sides. Door catches, emblems, locks, trim, and lights all of these have to be detailed and it is time consuming. Plus there is a fair amount of painted surface so decide what you want to do with that area. I posted my project with pictures under a thread in Classic Motorhomes- titled "Exterior Completed" (I hope that's the title) If not e-mail me and I will find it for you.
2015 Coachman Freedom Express 19RBS, Chummy IV- Ford Excursion- 7.3 Turbo-diesel