onempty

I also did not know about early 99 cars having a different IMSB. How do you know if a car has the early one or the later one?

KoB

According to Pedro's Garage, "Porsche made the first revision of the IMS bearing in model year 2000 going from a double-row bearing in the earlier models to a single-row bearing." So, a '99 will have the double row bearing (which is generally considered to be more durable). Some '00's will have a double row bearing; it probably depends on VIN or build date (FWIW, my '00 was built in 10/99 and had a double row bearing).