These six coupled engines were constructed with a leading Bissel truck that reportedly allowed it to travel smoothly around curves. The engines burnt coke, wood and coal during their lives. Large chimneys containing spark arrestors were fitted when using wood fuel. Coke fuel was discontinued from 1870.

Three of the engines were fitted with larger tenders ex D class engines before they were shipped to Maryborough in 1880/81. They were reboilered around the same time and the new boilers had the steam dome mounted further forward.