The twenty nine locomotives of the 1502 Class (based on the successful 1460 class that preceded them) offered a number of improvements over their older cousins. The new arrivals were fitted with the more powerful EMD 12-645E engines (the 1460 Class had been delivered with the 12-567C engines), and they were immediately put to work on freight and passenger traffic.

Whilst a handful of the class were sold to Tranz Rail (New Zealand) along with their 1460 Class cousins, the 1502 class weathered the initial mass-withdrawals faced by their predecessors. The majority of the class soldiered on until 1999 when they were set aside, replaced by 2260 Class units.

Six 1502 class were rebuilt using standard gauge bogies from 49 Class locomotives to form the 423 Class between 2002 and 2005. These locomotives were destined for use on NSW coal traffic for Interail, the interstate arm of Queensland Rail (formed by the purchase of Northern Rivers Railroad).

A large portion of the class has been sold to South American interests for rebuilding and use in Chile, and this has been detailed below.