Good Luck. I tried to find one used and had zero luck here just recently so I just ended up buying a new one. Got a nice deal from a vendor over Memorial Day. I have the 50qt and the ARB slide is awesome. I just got it Tuesday.
The Accuride 9301/9308 will make for a nice fridge slide setup. You can build this for ~$200 which is cheaper than any of the commercially available setups. They also work nicer!