A split spacer ring that is connectable to a cutterbar PTO drive shaft and works in conjunction with an anti-wrap shield to reduce the effects of crop debris accumulating on the drive shaft. Radial removal of the split spacer ring allows the anti-wrap shield to be axially displaced to enable sufficient telescoping movement of the drive shaft to disengage an end from a rotary cutterhead connection and thereby remove the drive shaft or other cutterbar components for repair or replacement. Improved axial clearance provided by the removed spacer ring also facilitates installation and removal of a crop conveying drum that may be installed on the drive shaft.