{HEAD ~ A common optical pickup} can be mounted in {TAIL ~ any} of disc drive units having respective pairs of oppositely disposed guide shafts that are separated from each other by different distances 
mounted in
{ HEAD ~ A common optical pickup } can be mounted in { TAIL ~ any } of disc drive units having respective pairs of oppositely disposed guide shafts that are separated from each other by different distances
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH