I need help identifying this piece of OLD cast iron. Railroad part? Sleigh part?

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Let me give you a little history. My dad found a piece of 35 pound cast iron in the mountains of Wyoming. It says "Sweet 1875" on one end and "Patent Oct 19" on the other. It weighs about 35 pounds and is about 1 foot long and and about 6 inches thick. I have tried to do research on it and not having much luck. What I DID find.. doesn't help me much because it doesn't show the full picture. What I found was that it MIGHT be a sleigh part. I found this by entering all the words on it in the search engine and I come up with this http://tinyurl.com/52tbjn.. if you are wary of clicking on the tiny url link.. this is the full link http://www.google.com/patents?id=NU9KAAAAEBAJ&pg=PA1&source=gbs_selected_pages&cad=0_1#PPA1,M1 The matching wording leads one to believe it is a part of a sleigh used for heavy cargo. However, I posted these pics (which I will have to post as I reply to all of you) in the ebay community forum, some there say it MIGHT be a railroad "re-railer" used to put derailed cars back on track. It would be spiked into a tie, and then the train would be pulled forward and the re-railer would guide the wheel back on the track. My dad wants me to sell it, but I obviously don't want to post it until I know with some certainty what it might be. I will tell you that where he found it, there were no railroad tracks anywhere to be found. I will post the first pic and post more as I respond to each of you. Thanks so much! THESE ARE NOT REFERRAL LINKS These are to give more info about what I am posting about