A roll mounting apparatus for the lower bale forming roll of a round baler enabling the roll to be selectively installed in one of two positions using common mounting components. The normal roll mounting aperture in the side wall allowing the roll shaft ends to extend therethrough is elongated to permit limited radial movement of the shaft. A reversible adapter connected to the main frame (one on each main frame side wall) at each end of the shaft covers a portion of the elongated aperture and provides a mounting connector (threaded hole) to replace a fastener receptacle eliminated by elongation of the aperture. By repositioning the adapter, the shaft may be displaced radially to one of two positions, thereby allowing the roll to be installed in an optimum location for the crop material or to enable manufacturing flexibility. The roll can easily be relocated to the other position, as necessary, using bolted connections securing the adapter to the side walls and the roll shaft bearing to the frame and adapter.