The problem you may have with this is the pivot shaft. They get stuck in the bearings and can be a real problem to get out. Search the forums, and you will find more than one case where the only solution is to cut the swingarm and pivot bolt with a sawzall.
The pivot should just slide out when you take the nut off of the one side. If that happens, I would recommend replacing the pivot bearing, the axle bearing, chain and both sprockets. Nothing should move back there when it is good.
ATCnut
82 185s - sold
83 200x (hopped up)
84 200x (stock)
84 70 (lost this one to the DMV)
85 70 (soon to have lights, a foot brake, and CDI ignition)
84 200es (parts trike) - sold
85 350X (the best)
85 350X (siezed motor, dream of a poweroll kit someday)
85 250sx (frame was trash, got parted out)
86 250sx (the tractor)
86 250sx (a nicer tractor)
86 250sx (an even nicer tractor)
87 200x (parts trike, its really rough, a dog was chewing on it for a while)
87 250es Big Red (the tank!!)