A system and method for measuring the preload condition of a vehicle differential gear assembly includes a multi-axis load cell having a spherical load button. The differential assembly is supported by the pinion shaft and the load cell button is positioned within a carrier housing hole. The pinion shaft is then rotated relative to the housing resulting in the housing to rotate along with the pinion shaft and abut against the load button. The resulting force against the button is measured in three orthogonal directions permitting an accurate force vector to be determined. The bearings preload is simultaneously set by applying an axial compressive force against the bearings while the pinion shaft is rotated.