Mike,
I installed low speed worms in the AM Baldwin S12 diesel loco, scale version. Disassemble one truck first and if necessary, shoot photos as you go. Don't forget the thrust washers. I cleaned the worm and gears in dish soap to remove the factory grease, polished the contact areas in the frame then applied LaBelle grease for plastic. (The wheelsets in the photo are Proto64 replacements from Northwest Short Line.)