A toner cartridge for use with an imaging unit in an image forming device, comprising: a housing having a top, a bottom, a front and a rear positioned between a first side and a second side of the housing, the housing has a reservoir for holding toner; a developer roll rotatably positioned on the housing, a portion of an outer surface of the developer roll is exposed along the front of the housing for supplying toner from the reservoir to a corresponding photoconductive drum of the imaging unit; an interface gear on the first side of the housing rotatably coupled to the developer roll, at least a portion of the interface gear is exposed at the front of the housing for mating with a corresponding drive gear of the imaging unit and receiving rotational force from the corresponding drive gear of the imaging unit; a first alignment guide extending outward from the first side of the housing and a second alignment guide extending outward from the second side of the housing for positioning the toner cartridge on the imaging unit, the first and second alignment guides are spaced above the developer roll along the front of the housing, the first and second alignment guides define a pivot axis about which the toner cartridge is pivotable relative to the imaging unit when the toner cartridge is installed on the imaging unit; and a first engagement member on the rear of the housing for receiving a bias force from a corresponding first hold-down on the imaging unit for biasing the toner cartridge about the pivot axis when the toner cartridge is installed on the imaging unit, the first engagement member is positioned closer to the first side of the housing than to the second side of the housing and is positioned next to the bottom of the housing, the first engagement member includes a first angled contact surface that faces upward and rearward for contacting the corresponding first hold-down on the imaging unit when the toner cartridge is installed on the imaging unit. a housing having a top, a bottom, a front and a rear positioned between a first side and a second side of the housing, the housing has a reservoir for holding toner; a developer roll rotatably positioned on the housing, a portion of an outer surface of the developer roll is exposed along the front of the housing for supplying toner from the reservoir to a corresponding photoconductive drum of the imaging unit; an interface gear on the first side of the housing rotatably coupled to the developer roll, at least a portion of the interface gear is exposed at the front of the housing for mating with a corresponding drive gear of the imaging unit and receiving rotational force from the corresponding drive gear of the imaging unit; a first alignment guide extending outward from the first side of the housing and a second alignment guide extending outward from the second side of the housing for positioning the toner cartridge on the imaging unit, the first and second alignment guides are spaced above the developer roll along the front of the housing, the first and second alignment guides define a pivot axis about which the toner cartridge is pivotable relative to the imaging unit when the toner cartridge is installed on the imaging unit; and a first engagement member on the rear of the housing for receiving a bias force from a corresponding first hold-down on the imaging unit for biasing the toner cartridge about the pivot axis when the toner cartridge is installed on the imaging unit, the first engagement member is positioned closer to the first side of the housing than to the second side of the housing and is positioned next to the bottom of the housing, the first engagement member includes a first angled contact surface that faces upward and rearward for contacting the corresponding first hold-down on the imaging unit when the toner cartridge is installed on the imaging unit.