You're probably thinking of Bob Maynard's design which started, I think, in the 11/77 issue of "Live Steam".
Also consider Kozo Hiraoka's excellent construction books on various types of geared locomotives. They were published by Village Press, the publishers of "Live Steam" magazine. May be out of print now but Amazon may have copies.
Google is your friend. Search on some of the keywords above and you ought to be able to find something.