It is - you're good to go.
As mentioned, it's possible to get the AOS w/out the bellows. In fact one of the previous iterations (Porsche is currently on 5th version, 4th revision based on the .04 part # ending) might not have automatically included the bellows. Not sure but could be possible.
Bellows are known to go bad on their own w/ or w/out the AOS being bad. Thus why you can buy them separately. Just order the part # I listed above and you'll have what you need (plus a dab of grease for the rings) to do the job completely.
Go to it
