I went to Colonial Choke and Tool's website and sent them a message.
They were very quick to respond via email and I sent pics, along with some measurements they asked me to take.
They are confident the extended choke is theirs, so I went ahead and ordered a standard flush full choke (because you need one of those anyway) to make sure.
I'll report back when I get it, but he seemed sure it was theirs.
When I confirm it, I'll order the others that you need in the stable (Imp Cyl, Mod, X-full, and probably a .665 turkey choke).
Anyway, they seem like a great company. Very helpful and very fast response.