A turbocharger assembly comprising: a housing (280, 290) comprising a bore (289, 291); a shaft sleeve that comprises a bore that extends between a compressor end and a turbine end, outer threads that extend to a first axial position from the compressor end, and an outer shoulder at a second, greater axial position from the compressor end; an inner lock nut that comprises inner threads configured to mate with the outer threads of the shaft sleeve and an axial length that is less than a distance between the compressor end and the first axial position; a bearing assembly (620, 630) that comprises at least one inner race axially located by the outer shoulder of the shaft sleeve and axially located by the inner lock nut; a cartridge (610, 810) received in the bore of the housing, wherein the cartridge comprises a cartridge bore, wherein the bearing assembly is received in the cartridge bore; characterised by: an outer lock nut (670, 870) that comprises outer threads wherein the cartridge bore comprises inner threads that mate with the outer threads of the outer lock nut; a seal element (663, 665, 863, 865) disposed between the bore of the housing and the cartridge (610, 810) and configured to allow radial movement of the cartridge within limits defined by the seal element; and a plate (910, 930) attached to the housing (280, 290) and having an extension (913, 933) received in a recess (613, 813) of the cartridge (610, 810), the plate and the recess dimensioned to limit rotation of the cartridge (610, 810) about an axis to a limited number of degrees and dimensioned to limit axial movement of the cartridge (610, 810) to a limited distance. a housing (280, 290) comprising a bore (289, 291); a shaft sleeve that comprises a bore that extends between a compressor end and a turbine end, outer threads that extend to a first axial position from the compressor end, and an outer shoulder at a second, greater axial position from the compressor end; an inner lock nut that comprises inner threads configured to mate with the outer threads of the shaft sleeve and an axial length that is less than a distance between the compressor end and the first axial position; a bearing assembly (620, 630) that comprises at least one inner race axially located by the outer shoulder of the shaft sleeve and axially located by the inner lock nut; a cartridge (610, 810) received in the bore of the housing, wherein the cartridge comprises a cartridge bore, wherein the bearing assembly is received in the cartridge bore; an outer lock nut (670, 870) that comprises outer threads wherein the cartridge bore comprises inner threads that mate with the outer threads of the outer lock nut; a seal element (663, 665, 863, 865) disposed between the bore of the housing and the cartridge (610, 810) and configured to allow radial movement of the cartridge within limits defined by the seal element; and a plate (910, 930) attached to the housing (280, 290) and having an extension (913, 933) received in a recess (613, 813) of the cartridge (610, 810), the plate and the recess dimensioned to limit rotation of the cartridge (610, 810) about an axis to a limited number of degrees and dimensioned to limit axial movement of the cartridge (610, 810) to a limited distance.