The 1600 class were built as branch line locomotives.

The first batch were delivered between December 1962 and June 1963, with the others arriving between October 1963 and January 1964.

A lengthy delay occurred before delivery owing to the first four being over the design weight.

They were initially based at Alpha in Central West Queensland[1][2][3] and at Roma in South west Queensland.

The 1620 Class followed on from the success of the 1600s, and were used in the central and northern areas of Qld.