I don't know about that JR, we only really have Cornish X (which we call Ross Cobbs) or Red Rangers (which we call Hubbards & Sasso Farm Rangers) and even then if you're not buying hundreds of them the suppliers don't want to know.
Luckily I know a guy that imports these slow grow eggs and a few other specialist types from France so I'm getting them while I can, as he will be retiring soon and then I'm stuck !!
This is the 3rd year I've had them and these look about the best yet, so will be keeping a few for breeding.
I have some Red Ranger types due in 3 weeks so will be interesting to compare to the ones you get over in the US.