A replaceable imaging unit according to one example embodiment includes a photoconductor unit positioned at the front of a housing of the imaging unit. First and second alignment guides extend outward at the same height from first and second sides of the housing, respectively, on the photoconductor unit and run parallel to each other along a front-to-rear dimension of the housing. Each of the first and second alignment guides includes a front contact member at a front end thereof and a rear contact member at a rear end thereof. The front contact members are positioned further outward sideways than the rear contact members. Bottom surfaces of the front and rear contact members are unobstructed to permit the bottom surfaces of the front and rear contact members to sit on top of corresponding guide rails in the image forming device to control a vertical position of the imaging unit.