A dual mode modular reproduction apparatus for selective different sheet printing modes with a common shared base frame unit (11) having integral module mounting guides (16) providing defined simple manual module mounting into the base frame unit into the same effective location of a xerographic engine module (12) with xerographic engine mounting elements (15) which mate with the module mounting guides (16) in the base frame unit for sheet printing xerographically, and an ink jet printing engine module (14) with mounting elements (15) which mate with the same module mounting guides (16) in the base frame unit (11) as the xerographic engine module to operatively mount the ink jet printing engine module in the base frame unit in place of the xerographic engine for sheet printing by the ink jet printing engine module. The xerographic engine module (12) and the ink jet printing engine module (14) are thereby readily manually interchangeable in the base frame unit (11) to provide a choice between xerographic printing or ink jet printing utilizing the same base frame unit. Preferably the xerographic engine module (12) is a monochrome printer, with a separate fuser module (50), and the ink jet printing engine module (14) is a plural color ink printer, and there is also a separate document imaging station module, mounted on additional module mounting guides in the base unit, to provide an easily changeable variety of different imaging products and shared components.