Abstract: Apparatus for precisely positioning the various work stations (e.g., image-forming, cleaning and image-transfer stations) of an electrophotographic printer/copier relative to the outer surface of a rotating drum, e.g., an image-forming drum or an image-transfer drum. Such apparatus comprises a pair of drum-support members, each having associated reference surface features adapted to mate with complimentary reference surface features on the individual work stations. Preferably, the placement of the reference surface features of the drum-support members are factory set to account for any idiosyncrasies (e.g., run-out) of a drum supported by such members.