Hello Vsmith I’am not sure how big the Gn15 project will be? But here is a link to a project Darth Santa Fe did on a Athearn Hustler. I don’t know anything about hustler’s so this may or may not help.
http://cs.trains.com/mrr/f/88/t/173909.aspx?sort=ASC&pi314=1
He does a great job on it. And few more guys show there projects. Wolfgang did a project on one to here is a link to his site.
http://www.westportterminal.de/
http://www.westportterminal.de/grandtline_25ton.html
He has some great stuff on there. Hope this helps Frank