I would change your impeller just to put your mind at ease , was always thinking about that part when it was gonna go , not knowing how old it was .
changed mine last year on my Honda like Scott said not complicated , ended up buying the whole impeller housing kit, instead of just the gaskets and impeller.
i made sure i had a torque wrench before i decided to do it, heard lots of horror stories bolts over tightened and stripping or cracking the aluminum .