A drive system for a fluid end of a reciprocating pump assembly including a drive member and a power end housing having a crankshaft rotatably disposed therein. The assembly includes a gearbox secured to the power end housing, the gearbox operatively connecting the drive member to the crankshaft for rotation thereof. The assembly further includes at least one arm member extending between the gearbox and the power end housing, the at least one arm member positioned to resist relative movement between the gearbox and the power end housing.