I think it might be for a 2” x 3” tool joint thread Rope Socket, but double check measurements as shown in pictures compared to what you need.
Cast numbers as shown in picture(s), but unsure if it is Trident, Rampp, Spang, Gil Rock Drill, Keystone or maybe another historical tooling manufacturer.
Put this piece of drilling history back to work on your cable tool water well drill rig
(Bucyrus-Erie 22W, 20W, Speedstar 71, Cyclone or similar spudder pounder),
Simply add it to your vintage / antique Americana history collection, or modify as needed to make it what you want to be (or whatever application you may have),
Used - Selling "as is", what you see is what you get.