What is the purpose of this wrench? I saw one on ebay and it has a U 50 that slid onto the U 51. Do they go together?
http://www.ebay.com/itm/ANTIQUE-INTERNATIONAL-HARVESTER-WRENCH-U50-tractor-wrench-ihc-tool-farm-barn-/321229312891?pt=US_Hand_Tools&hash=item4acac2537b

U50 & U51 / UA51  came with various IHC & Deering planters & seeders -- the hook on U51 and UA51 was either a spring puller or worked somehow with the flexible tubes that the seed flowed through on the way from the seed box to the planting shoe.  U50 is called "socket wrench" in the parts lists condensed in Gil Irps' IHC wrench compilation, and U51 / UA51 is called "socket wrench handle."

Thanks for the info. that answered my question. Kind of figured the hook wasn't for hanging purposes.

There's also a version of this wrench with only two openings. Its fairly rare. I have one but took several years to aquire it.