I have a couple of those smaller water pump pulleys. Not sure what they came off of ...they've been in my parts stash forever.
The smallest one is 5 1/16" across, 1" from face to center of belt groove.
The other is 5 3/4" wide, and 15/16" deep.
...
i'm also thinking there is a small [just a tick over 5" or a tick under 5"] single groove pulley used on some ac small block applications, but i can't confirm.
maybe the same as the small one in these pics.?.?... but i have no clue on its original application
