You can make one if you have a mill.
Back when SM was operating here, for some reason (seemed crazy to me) they sold the parts business. When they'd get a parts quote request and they didn't have it, they'd get a quote from a machine shop then double it, after which clausing or whoever it was would double it again.
Ergo, even if you can't make one, prepare a drawing and it should be 1/4 of the price from Clausing