Juniper J-series Services Router J2350 Hardware Manual page 195

Chapter 10: Contacting Customer Support and Returning Hardware
J4350 and J6350 Chassis Serial Number and Agency Labels
J4350 and J6350 Services Routers have serial number ID labels on the back of the
chassis, as shown in Figure 94 on page 171, and an agency label on the bottom front
corner, as shown in Figure 95 on page 171.
Figure 94: Location of Serial Number ID Labels
Figure 95: Location of the Agency Labels
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Locating Component Serial Numbers