Kadee publishes a "what fits what list" and it's always somewhere inside the big Walther's book. It's also on the Kadee website. I have discovered (the hard way) that you can save quite a bit of filing and hacking by checking the list and buying the recommended coupler in the case of locomotives. In the case of freight cars, a #5 works in nearly everything.
David J. Starr
Steve Hosk>