When I did mine I replaced the tensioner, as is often recommended when changing out belts, and it was NOT an easy "no tools required" job. The gatorback with the new tensioner took me forever to get back on, and it WOULD NOT fit without loosening the bolt that holds the tensioner in place, giving it just an extra little bit of play.

I'm not sure what the difference is, but some people have had very different experiences changing out this belt (as reflected in another thread a few weeks back) - some were simple 5 minute jobs and others like mine were much more of a PITA.

And BTW: I replaced mine around 80k+. The old one was all cracked to hell, but it was still holding strong!