I wish you good luck on finding one. I'm about 12 years in and still haven't found one. I guess I'm fortunate in the I still have the bottom half. The casting is so thin in this area that its obvious to see why the break so easily. I've been thinking about trying to reinforce the backside of the main piece and form new ones out of stainless rod - not original but still better than 1/2 missing. When I get around to finally doing it, I will forward my results.

The horn ring looks to be the same as 50 to 52 Chev. Should still be a few of those around over there.