Southern Cross made a number of pumps which "shared" the same sized gearbox - and this 5" x 5" is one of those. 

Pumps of this size, 5" x 5", have 2.5" inlets and outlets. At 50 strokes per minute, or 260 rpm, this pump will produce 2100 gallons per hour to a maximum head of 250 feet. It will need a 4 hp electric motor to achieve maximum capacity. To increase the speed, you would need to increase your motor capacity.

During the reassembly process after being stripped, sandblasted and dismantled, this pump has been fitted with the following new parts: crosshead pin and bush, piston plates x 2, centre plate, wet-end maintenance kit (buckets, valve rubbers, valve springs, gaskets and packing) and a pinion and shaft.

As per the photos, the gearbox is in excellent condition.