how big a job is changing a belly pan? What is involved? What kind of rivets to use? Steel?

easy job rocketman if your old belly pan is on there with rivits now just drill out the centre of all the rivits that are there now and they will fall apart and when you put it back on i would suggest using small bolts with locking nuts on the bottom of it, and it will hold up alot better, thats what i did because i couldent keep the rivits in the bottom, almost every time i would hit it they would pop out.

rocketman,
*ski-doo has the only rivets that size. watch when you drill the originals out that you do not drill too big and make a bigger hole. when you get the new rivets also get the aluminum washers that are needed not everywhere but in alot of them. not a hard job at all just takes huge time i have done it twice.
p.s. you'll need all yellow and two black ones.

Rocketman: be thankfull you don't have a PRS chassis sled. The tie rods & control arms went thru the rubber boot. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/mad.gif

You'll have to be able to lift & hold the sled from above as you'll have to remove the rear bolt of the trailing arms. With the hood off, bolts removed & the rivets drilled out, you just take the bellypan forward, working it over the suspension. Reverse the procedure to install the new one.

If you're going to install a skidplate. I'd say now would be the easiest time to 'doo it.

To much work for this guy. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/confused.gif
I have no ambition to work on sleds after wrenching all day on junk. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/exclamation.gif *http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/baaa.gif

I drilled out the rivets and replaced them with big self tapping steel screws. My belly pan had been replaced with a thisk peice aluminum (the guy rode the sled strictly on ice).