Shimano's threaded cassette cogs were all of the same threading, except for Dura-Ace which was smaller to allow making an 11t top cog. Yes, those were a thing back in the Uniglide days, even Suntour had been supplying 11t cogs for their freewheels.
The Dura-Ace threading was stepped down from the outside of the splined freehub body, so is easy to spot. The cogs themselves have a quite visibly-smaller ID as well, but you might have to look for a second to notice it.