This is a used stem all tang from a Mumm 36 mast. The mast is a Hall spars mast  but much of the rigging is Navtec, so I don't know exactly about this piece. It came in box of spare parts for the boat. Feel free to ask questions about the part and I will do my best to answer. 

The diameter of the threaded bar is 3/4" and the length of the threaded bar is 5-3/4". 

The threads  have some gunk and grease in them, but they are in good shape and the caps screw on nicely.