Just try them and see how they feel. One of mine vibrated out and I replaced it with one I got at work so I don't think they are a big deal. If they don't fit just pick up some from the hardware store. EDIT: I just called my brother and he said he used the stock ones. So your good.
Well, my stock mufflers had threads built in so they just had some bolts that screwed directly into them, and the cycle shacks had a square nut and bolt set up... A square nut that fit into a slot and a bolt to screw into it. That made it somewhat adjustable forwords and backwords (didn't have to line up perfect) If the shacks just have that slit and a notch then you may need to get a nut from the hardware store as the stock ones don't have a nut.
yeah thats the way mine is the stock just screwed up into the stock pipes, the cycle shacks have the slot open on one end. thanks guys.
Yeah so maybe you can find a square nut the right size to fit in there, that way it wont spin when you tighten it... Can't immagine it would be easy to fit a wrench inside there. You should be set then though, and you will love the sound! Awesome compared to stock! Good luck.