Jim;

When I first read your post, it didn't compute for me either...in all the Driveshafts I've ever come across (both early and late center Bearing supports styles), I don't ever recall having seen a felt seal or suggestion that there should have been one...so I waited for other, wiser wrenchers to chime in so that I might learn something new also...

So now that other posters have chimed in, I have to agree with C1800 and Derek and ask, what would it need to seal in, in a sealed bearing?...also...are you certain there is supposed to be one...? What makes you believe there is supposed to be a felt seal, or was one before it disintegrated...? Maybe a PO put it in there additionally, to keep dirt out of the Spline joint (actually not such a terrible Idea, although the Rubber Bootie should do that pretty well!)... also, if "The felt seal is completely disintegrated", what makes you believe there is supposed to be one? Can you maybe post a pic of the area in question, or maybe reference an Item number in the exploded assy diagram.

http://www.sw-em.com/Driveshaft_and_U-Joint_Notes.htm

...more questions, than answers...!