Since you mention it, Chicago Flyhouse shows one in one of their videos. Looks like a custom part? They don't list a catalog on line, but they might be able to hook you up.
I bought a few of these from Sapsis Rigging just a few months back. (Silver lining: Plenty of downtime lately to do theatre maintenance.) I don't know if they have any more in stock, I might have bought the last! but it's worth asking. www.sapsis-rigging.com
Thanks, and yes I'm west of the windy city. Funny you mentioned Ted, I met him here the other week but wasn't thinking about this at that time. We were frying some bigger fish. I'll give him a call.