999 201 321 00 is the needle bearing for the original clutch fork design. The updated setup moved the needle bearings to the trans. bell housing and plastic bushings were substituted into the clutch fork.
I assume the bulletin was released sometime after April 6, 1989?
Since the later cars (964 and 993) use the same setup, I have to think the bulletin shortly followed the factory installation of these updated parts. Surprising that the original needle bearings were still available in 2002. I would have thought Porsche would stop supplying them.