Joined: Nov 2006
Posts: 19,810
Likes: 597
From: NJ, NYC, LI
Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...
Sturmey Archer did make aluminum alloy hub shells in the 50's, but I don't know if they were still being made as late as 1970. The ones I've seen had the word "ALLOY" stamped on them.
Try a magnet on 'em?