Well...
If you can get parts from the Back Shop these days, they have a wonderful Brass (or Nickel Silver if you request it) Extended Knuckle that fits into the Kadee's. You have to remove the Kadee plastic knuckle and fit everything together just right.
On the Same Spru is an split shank cast as well. You have to spot and drill a hole into the top of the Kadee shank and ACC the brass split shank. I have done about four of them already and plan to do more. They look and operate wonderfully. The pattern work for this was done by Dave Squire.
I don't know the part number off the top of my head...
Kevin Cook