The Kadee coupler is not sprung. It is a tight fit so it won't flop around, but it can move a bit. With small industrial locomotives you can normally get away without using the Kadee draft box as the sideways offset is never too great.
If you look at??you can see a two level coupler pocket at the front of the Hunslet locomotive and you can just see an autocoupler adapter that is hooked into the coupler pocket at the rear.
Regards,
Michael Milway
Unanderra, Australia
