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