If you're talking about an AW or AWC, they're awesome, and the older, the better. (They will have a date code on the hubshell.) One of the most commonly found hubs on planet earth, too.
If you're talkin about the TCW or S3C, those were kind of unreliable as far as braking goes. Most other SA 3 speeds were pretty awesome, but the AW is the IGH version of the Ford 300cid six. Reliable, runs forever, but no glamor points at all.
Hit up sheldonbrown.com and search for sturmey archer. Tons of info there. Your model ID is on the shell, by the date