As these cars age, the clutch fork tips wear, the clutch fork bushings wear, the cables stretch, the clutch cable bushing at the trans deteriorates, and the clutch pedal auto adjusters frequenty stop working.
Add to this the stamped steel races in the Rev B bearing, whether ceramic or factory produced, can vary in their axial stackup tolerance because they are stamped, not ground (and am sure the remaining stamping tool is getting pretty worn out by now)..
So, there are 6 or 7 different things that affect the axial position of the bearing in relation to the pressure plate fingers. These clutches were designed to have the TOB constantly turning, in other words constantly in contact with the pressure plate fingers. If there is too much clearance in any part of the system the TOB will not make good contact with the pressure plate fingers. With the intentional radial clearance built into the bearing, it can then "orbit" and rattle that way. Or it can rattle as intermittant contact is made between the inner race and the fingers, assuming one or more things that affect the stack are allowing for addtional clearance.
Finally, ceramic does not have the same dampening characteristics as steel, so the bearings will tend to be a bit noisier.
If lightly pressing on the clutch peddal makes the rattling go away, check the cable bushings at both ends, try to manually adjust (there is a very good post on here somewhere on how to do this), if that fails replace the clutch cable.
If you are doing a clutch, consider the filled nylon fork bushings from SHOnut, or replace with factory Ford, check the clutch fork for wear vs. service limit in the manual, etc.
