The second class of locomotives of the Tasmanian Government Railways which carried the letter M was a Pacific introduced in 1951. This letter had previously been used by a Garratt, the last of which had been withdrawn in 1931. They were designed for passenger traffic on the Hobard-Launceston line and had to be powerful with an axle load of not much more than ten tons. They were similar to the Indian class YB, but had modern features like the use of welding on many parts and roller bearings on all axles of the locomotive and tender. The minimum curve radius was 330 feet. 

Since dieselization was already on its way, only ten were built. In 1957 and 1958, four were rebuilt for freight traffic and called class MA. They now had drivers of only 48 instead of 55 inches and due to changes in weight distribution, adhesive weight had being increased by a ton. Withdrawals already commenced in 1960 and were completed by 1975. All have survived to this day in various conditions, with some still being used on heritage railways.