QR decided the last 30 locos built by Clyde/Walkers would be used for passenger and general freight work, rather then export coal traffic. These locos became the 3900 class.

They were higher geared than the 3500/3600s and had frame hung traction motors to allow higher speeds.

The 3900s worked passenger and freight trains between Brisbane and Rockhampton. Freight wise, they hauled everything from cattle, grain, molasses and general containers. All 3900s were based in Rockhampton.

Ironically, these locos began working as slave/remote locos on the Central Qld coal trains due to various problems with them leading in general freight service. The 3900s placed in coal traffic were being fitted with access ladders and identified with a \’C\’ suffix. A number of members of the class in coal traffic were being overhauled and renumbered as the 3551 class. Modifications include being fitted with new 3500 class bogies with axle hung traction motors and lower gearing with speed limited to 80km/h. 3556 (ex. 3906 – Petrie Derailment) was the prototype.

The only 3900 out of service is 3902, which was scrapped in January 2001. 3902 was involved in a collision at Beerburrum in \’94.

The 3900s are now a piece of history, with a relatively short working life on freights and passenger trains between Brisbane and Rockhampton. Many have now been converted into the 3551 Class for Coal Traffic in Central Queensland. The last 11 in service are being partly converted to 3551 class except that they will not be geting new bogies or being re-geared. 3918 had the honours of hauling one last suburban passenger train on the Farewell 3900s tour on 18 April 2005.