Used tracks fit the following models: QUADTRAC 550, QUADTRAC 580, QUADTRAC 600, QUADTRAC 620, QUADTRAC 500, STEIGER 380, STEIGER 385, STX375, STX380, STEIGER 430, STX425, STEIGER 435, STX430, STX450, STX480, STEIGER 480, STX500
Inner lugs in really decent shape and treads are fairly decent as well. One track has a minor tear on the edge but doesn't appear to have affected the cables.
$7000 for the pair, $4000 if picking one.