The seals everybody is talking about are probably the 2 orings that are behind the chaincase that are on each shaft. Usually they are fine to reuse. The main one is the one for the cover. Most generally they are ok to reuse. Just make sure it does not have any cracks or rips in it. I usually put a very small bead of silicone on it just to be sure. That year sled you do have to remove the chaincase.