1. A method of changing drive equipment of a mobile power unit, the method comprising:operating a first mobile power unit in a first configuration in which a gas turbine engine of the first mobile power unit drives a drive shaft through a reduction gearbox, the drive shaft being connected to a pump to drive the pump to provide high pressure fluid, such that the drive shaft has a maximum speed of rotation in a range of 1000 RPM to 1700 RPM;
receiving one or more signals indicative of an electrical demand or fluid requirements of a well pad site;
determining, based at least in part on the one or more signals, that the electrical demand is greater than an electrical supply or that a fluid capacity is greater than the fluid requirements; and
interchanging, based at least in part on the determination, the first mobile power unit from the first configuration to a second configuration by changing the pump for an electrical generator by replacing the pump with the electrical generator, in the second configuration the gas turbine engine of the first mobile power unit drives the drive shaft through the reduction gearbox and a generator gearbox, the drive shaft being connected to the electrical generator to provide electrical power, the generator gearbox at least partially offsetting the reduction gearbox.