So far as I know, there were three different disk plows for the cub. A mid mount for the standard hitch, a mid mount for the fast hitch, and a rear mount. Each of them cuts about a 12 inch furrow, with the midmounts weighing about 75 to a hundred pounds. The midmounts are great for plowing gardens, etc. since they don't add anything to the length of the tractor, which makes turning at the ends easier. The rear mount works better if you are plowing under rougher conditions, since it doesn't shove the tractor to the side as easily. It does however add about 4 feet of length to the tractor, and is fairly heavy. The trail wheel which steers, and serves to hold the plow in the furrow is weighted, and weighs about a hundred pounds by itself. The entire plow probably weighs aobut 250 to 300 pounds. If you are not already familiar with disk plows, they are great for most uses, but when turning sod do leave it very rough.
As far as finding one, watch local auctions, or salvage/used equipment dealers. 2 places to try would be http://www.jptractorsalvage.com
If they don't show them on the web sites, email or call them. A last resort would be Ebay.