There are three gauges common in Japan. Most mainline trains were built to the Swedish standard of 1067mm (3' 6") which became so popular through the Pacific and South African regions. The second, for mountain branch lines, was 762mm (2' 6"). Most of those have been converted to 1067mm, but one line across the bay from Nagoya is still actively carrying passengers on 762mm rails. They use quite attractive EMUs. The third standard is (can you guess?) naturally 1372mm (4' 6"). That's why Japanese n-scale is 1/150 rather than 1/160. They're modelling trolley gauge....including the old Japanese standard which is narrow gauge by North American standards, and especially among them the Kiha 80 series and their later derivatives. although there's a narrower gauge system, even for Japanese standards that i forget the name of, and don't much care for either its earlier nor later color scheme, but the equipment is really, or looks like in the pictures, which is all I know of it, just right...
Standard gauge used to be an oddball, only used for American style subways like the Marunouchi and Ginza lines, but most commuter lines which started as streetcars have converted to 1435mm (4' 8.5" standard gauge).
If you run across the Narrower gauge you were thinking of, let us know. I'd like to know what it is.
Might be a good idea to say in what country &/or state they were/are mainly used in.
I found the DD17. It's a tank engine indigenous to the Queensland area. http://www.home.railscene.com/zanatta/loco/dd17.htmDD17 - 1046/7/9
http://www.youtube.com/watch?v=NaUUCB6-GCM
It looks like it's propane fired, now.
Claude