Agilent Technologies 53147A Assembly Level Service Manual page 127

Appendix A Rack Mounting the Instrument
Rack Mounting the Instrument
5 Position the rack-mount panel (53147-60211) on the front of the instrument
so that the four holes in the top and bottom of the rack-mount panel are
aligned with the four threaded holes in the top and bottom of the
instrument (the holes that were used to mount the front bumper retainers).
Assembly Level Service Guide A-3