If the previous owner had taken it sand duning 90K on the stock clutch is really good. Sand is the toughest off road medium on an off road vehicle. The added torque needed to glide a jeep over sand puts a heavy strain on a clutch or automatic transmissions, and take years off both if not properly maintained. Changing fluids every couple of years inspecting and replacing of clutch and pressure plates, shocks ect ect.
The silica in the sand acts like an abrasive powder and wears out the moving parts on any sand buggie out there. This powder is in the fine dust and there is now way to keep it out. Air filter wraps and other assorted aftermarket products keep it out some what but you will find that it gets into places you never thought it could. Dropping your oil pan and sifting through the pan sediment will tell you if your going to have any engine problems down the road.
A thorough inspection of all under carriage parts including the wheel bearings and spindles should be inspected for glazing or wear.
All moveable suspention parts should be checked ,I.E. the bushings and shoulder bolts for wear.
Draining and opening of both differentials for a good inspection would also be on the menu since a locked up diff at 60 miles per hour is a experience that you dont want to share with the board later on.
And dont forget to take a good look at and servise all your U-Joints as well.
I am sorry about the length of this post but years of sand duning has tought me the finer points of maintaining my quads to the point of being anal over it. A five mile walk through the sand dunes to get help sucks wearing riding boots