I have a 2002 mountain max, here is the rundown on it: 141" 2" paddle track, 600/700 sx (redhead) engine. Has the 2000+ skid improvements and geometry. Only problem with the stock sled is the track. It has a horrible pattern and the durometer is too hard. If it has been trail ridden then the track will start throwing lugs like mine was, it's only a matter of time. Set up properly (limiters, shock preload) it can be pretty capable as a hill climber, but if you want to just bust drifts in a farmers field it will be a blast as is. If your willing to invest into it, you can go full blown mod sled and end up with a very capable sled for about half what a new mtn sled will cost. It will out run most modern 600's and can hang with the 800's. You can't beat the torque of the 700 triple and it will never leave you stranded.
Full run down on mine: 151" track, rail ext & tunnel. Bars/risers/t-post. Light weight can. New skis. Stripped skid. Low windshield. Custom seat. Into mine about $5000-5500, paid $2000. Biggest bill was the track swap, $1800 parts and labor but I was a chicken and wanted the dealer to do that part. They ended up doing full driveline bearings and a chain so I'm glad they had it to look it all over. Probably shed about 35 lbs by the end.