Originally Posted by Dave Mayer

Another thing: we have buckets of Shimano and Shimano-type rear cassette hubs designed for 6 and 7-speed drivetrains. So 126mm rear spacing. Most of these do take Hyperglide cassette cogs. Some of these old hubs were designed for the older clunky Uniglide cogs, but a few minutes of grinding on each cog will render a Hyperglide cog to be Uniglide freehub compatible.