The 782 mule drive is the same as the one used for the QL series.
All of the parts you listed; "ratchet" (right name.... but I always thought it odd), spring, and j-bolt are all available new from CCC. Honestly, the only thing not available new is the actual main bracket. One of the idler "arms" is ridiculously priced.... but all the rest is somewhat reasonable.
http://www.cubcadet.com/equipment/AR...0-A/0074200005