Abstract: An improved centrifugal pump of the end suction type having a mechanical seal and a ball bearing contained in a unique stuffing box about a rotating impeller shaft. The box positions the bearing close to the impeller and reduces the bending movement of the shaft at the seal in severe services, e.g., pump startup conditions in drilling mud systems. Also, the box is arranged for the ready removal or replacement of the machanical seal or bearing. The pump has a casing defining an annular chamber wherein an impeller is driven by rotatable pump shaft. The box is mounted in a cover secured to the casing. The cover has a concentric central opening providing an annulus about the shaft. The box is seated by step surfaces in the central opening and secured to the cover by bolts. The mechanical seal is mounted about the shaft against an inwardly facing stepped surface within the box.