Reese 1-7/8-in Lawn Tractor Hitch Ball in the Trailer Hitch Balls department at Lowes.com
Amazon.com: OPENROAD Adjustable Trailer Hitch Ball Mount Fits 2-Inch Receiver, 2" Tow Balls 7500lbs, 9-1/2" Drop/ 8-1/4" Rise Drop Hitch, Tow Hitch for Heavy Duty Truck with Stainless Steel Pins and Lock :