I have been doing lots of work on kadees, I have modified some of my stock, and researched a lot.
It seems very complex, with a bewildering array of kadee types and fixings.
It isn't helped by the fact that the NEM standard that should help and is bandied around alot is both poorly adhered to and poorly explained...
There seem to be two relevant standards -
The NEM 362
http://www.miba.de/morop/nem362-d.pdfand the NEM 363
http://www.miba.de/morop/nem363-d.pdfthough everyone seems to just talk about NEM coupler pockets.
Whilst I have found the Kadees for NEM (17 though 20) work ok in the 362 pockets, they rarely seem to work well in 363 in my very limited experience.
Sorry can only find the standards in German, think may have to get them translated.
There also seems to be a real need to gather everyone's UK conversion experience together and no-one has really done a solid job on this.