1Co+Co1

This was accomplished by the addition of a non-powered axle in an integral pony truck to the three traction motored Co powered bogie.

As a prior supplier of steam locomotives for the SAR, ALCO appeared to be virtually assured of receiving the order.

General Steel Castings had a design on paper for a 1Co bogie which could be utilised by either ALCO or GE and which would enable the SAR's specification to be met for the heavier 1,800 horsepower (1,300 kilowatts) units.

[1][page needed][4] Between 1959 and 1961, the SAR placed 115 high-nosed Class 32-000 GE type U18C1 diesel-electric locomotives in service in South West Africa, where very light rail conditions necessitated lighter axle loadings which could not be achieved with conventional three-axle bogies under a heavy 96,520 kilograms (95 long tons) locomotive.

Apart from the bogies, which necessitated a smaller fuel tank, its physical dimensions and exterior appearance were identical to that of the Co+Co Class 33-000 and it used the same V12 prime mover.