They are EMD model JL8 (J = Double Ended Cabs, L = Lightweight Frame, 8= 8-cylinder 567 engine) and although originally fitted with an EMD 8-567CR 8 cylinder engine of 960 horsepower (720 kW), all were later fitted with 645 type "power packs" (piston & liner assemblies) for parts standardisation. The original power output was kept for reliability reasons. They weighed 67 tonnes and had a maximum speed of 123 km/h (76 mph).
Many were later rebuilt with a GM 8-645E engine of 1,100 horsepower (820 kW) (as used in the re-engined Class C locomotives), though some have since had the original engine refitted. The engines were delivered in the CIE livery of brown/black/white.
