Keen eyes may have noticed, the KiwiRail DM class locomotive model page was updated this week. Testing has concluded that the Kato SD80/90mac N scale mechanism is the best fit for this locomotive shell. These mechs sell for between $150 - $250 so make a good and affordable combination with a DM class locomotive shell.
Unfortunately, testing has also revealed that the design has a few issues to be worked out. I will be updating the design in the coming weeks. I am also looking at etching the handrails on the long hoods, and potentially putting etched grilles in place as well. Watch this space!