I think it would be a good idea to go ahead and add the ball gusset's. Will I have to take the knuckles off to do this. I've already go them on and ready to mount the wheels and I won't be taking back apart any time soon just to do it. I would be consered about messing up the wipers and gasket.
the felt and rubber ring should be takin off, but you could probable do it with them on.
the inner seal should probable come off too, but its your call.