I wanted to add that the trucks used in the engine are made fairly well. I just hate the plastic axle gears that manufacturers use and they split when they get older. The Delrin upgrades that NWSL sells seem to be working well for me. Here's a pic inside the K-line truck, down a bit on this page:
http://www.gscaletrainforum.co...-detail-look-inside/
1Thing to note is that K-line apparently made two different models of G scale trucks that have different tooth counts. The Army version was a different later model than mine, I believe?