Randleman. mine both broke as well and I could not find a replacement part at all and I tried everywhere.
I finally found a boat building suplier. They state on the website that they only sell to boat companies, but when I called I spoke to a women and she hooked me up. SInce that time, two more members picked up the same type of ball floor drain. When or if you call, they may say no, but just drop my name and say a few guys recently bought some. They will only sell two at a time.
I know you wernt to happy with the valve drain set up, but trust me on this one, these work great.
http://www.thmarine.com/