Thanks for posting your project. I came here to research my own. I bought a 3 acre place west of Rye, Colorado 20 years ago and the previous owner left a McCormick - Deering on it with his widow. The realtor bought it from during my purchase, bit he never picked it up.
Since my cell phone reception is pretty lousy I sometimes go out and sit on it because it is a high spot. It looks in pretty good condition other than the wood portions. I do carpentry and painting in the city 30 miles away, so I imagine rebuilding a tongue is not beyond me, I just have no idea of the correct dimensions.