Brian Baylis is right, most 1970's alloy freewheels are conversation pieces, they are not serious equipment for day-in, day-out use. The teeth wear quickly and the ones with alloy bodies develop cracks or the remover interface gets mangled.
I have a suntour Winner 1st-gen alloy (5 speed, 1975), and an everest (6 speed, date unknown), and a Maillard alloy freewheel (6-speed). I also have a Suntour Microlite (60-speed, late 70's.) I'll try to weigh them all and post the gear ratios and weights.
I bought them as conversation pieces to mount on weight-weenie bikes when I'm trying to show off.
The maillard (used on raleigh team pro's starting in 1974 or 1975) is likely the lightest, as it is the only one circa 1975 with an alloy body. These are still available NOS and in stock at Euro-Asia Imports, according to the online catalogue.
In my opinion, the Suntour Microlite Winner will beat all the other freewheels, at roughly 180 grams complete (alloy body).
- Don Gillies
San Diego, CA, USA