| In March 2003 a contract was awarded to Siemens Mobility for the rebuilding of three Class 3200 into Class 3700 locomotives as prototypes for a proposed rebuild of the entire class. The work was undertaken at United Group, Townsville. The 3100/3200 are electric locomotives built by Comeng with Hitachi supplying the electrical equipment. Two separate classes were built between 1986 and 1989, 19 Class 3100 command units that could lead trains, and 67 Class 3200 slave units. |