I have two wheelsets with Shimano 600EX hubs and "clusters" that looked superficially identical. Using the codes on the hubs I have a 1984 "cluster" part no MF-6207 and a 1988 "cluster" part no MF-6208.
The strange thing is that the later part (MF-6208) is a freewheel. I know this as I have removed it from the hub with my trusty Park Tools freewheel extractor. After cleaning I can now see it has a "silver" coloured plated finish (cad???).
The other "cluster" turned out to be different. I could not find any splines! Because it is an earlier part I had thought it must be a freewheel as well. But after researching this site and Sheldon Browne I think I have an early Shimano uniglide freehub cluster. The cluster is a matt black finish and has the notation "unscrew" with an arrow pointing in clockwise direction on the outer surface.
Hints please on how to corectly remove this cluster (if that is what it is).
Do I really have a 1984 uniglide cluster, and if so, why did Shimano make freewheels in the 600 groupset after they had introduced freehubs???