A toner cartridge , comprising: a housing having a top , a bottom , a first side and a second side positioned between a first longitudinal end and a second longitudinal end of the housing , the housing has a reservoir for holding toner; a photoconductive drum rotatably positioned on the housing , a portion of an outer surface of the photoconductive drum is positioned along the bottom of the housing , the photoconductive drum includes a rotational axis that runs in a direction from the first longitudinal end to the second longitudinal end ; and a boss protruding outward from the first longitudinal end of the housing at the rotational axis of the photoconductive drum , an outermost axial segment of the boss along the rotational axis of the photoconductive drum includes a partial cylinder having a cross-sectional shape of a circular segment of less than 360 degrees circumference, an outer circumferential surface of the partial cylinder is convex to the bottom of the housing and forms a bottom contact surface of the boss that is unobstructed to contact and sit in a corresponding V-block in an image forming device when the toner cartridge is installed in the image forming device , the outer circumferential surface of the partial cylinder has a radius, the outermost axial segment of the boss includes a clearance above a topmost portion of the partial cylinder and within the radius of the outer circumferential surface of the partial cylinder permitting the clearance to accommodate one or more features in the image forming device during installation of the toner cartridge into the image forming device . a housing having a top , a bottom , a first side and a second side positioned between a first longitudinal end and a second longitudinal end of the housing , the housing has a reservoir for holding toner; a photoconductive drum rotatably positioned on the housing , a portion of an outer surface of the photoconductive drum is positioned along the bottom of the housing , the photoconductive drum includes a rotational axis that runs in a direction from the first longitudinal end to the second longitudinal end ; and a boss protruding outward from the first longitudinal end of the housing at the rotational axis of the photoconductive drum , an outermost axial segment of the boss along the rotational axis of the photoconductive drum includes a partial cylinder having a cross-sectional shape of a circular segment of less than 360 degrees circumference, an outer circumferential surface of the partial cylinder is convex to the bottom of the housing and forms a bottom contact surface of the boss that is unobstructed to contact and sit in a corresponding V-block in an image forming device when the toner cartridge is installed in the image forming device , the outer circumferential surface of the partial cylinder has a radius, the outermost axial segment of the boss includes a clearance above a topmost portion of the partial cylinder and within the radius of the outer circumferential surface of the partial cylinder permitting the clearance to accommodate one or more features in the image forming device during installation of the toner cartridge into the image forming device . <EOS>