Total Stations from Topcon are very consistent in their serial number placement. The serial number can be found on the left upright on the eyepiece side of the instrument.
HiPer SR or HiPer V: Printed on the bottom of the receiver
HiPer HR or GR-3 / GR-5: Located under a hot-swappable battery
HiPer II: Silver Sticker on the side of the unit
FC-500 / FC-5000: Printed on back of device
S-10 / FC-2500 / FC-2600 / Tesla: Found under battery
FC-25 / FC-236 / FC-336: Printed on side of device
Machine Control Components
Clearly printed on the outside of the component (side or rear) on a silver sticker containing part number and serial number.