Attached to this post are PDF's of the service manuals for the Xserve G4, G5 and RAID. Enjoy :)
xserve.pdf - Xserve, Xserve (Slot Load), and Xserve (Cluster Node)
XServeRaid.pdf - Xserve RAID
xserve_g5.pdf - Xserve G5, Xserve G5 (Cluster Node), and Xserve G5 (January 2005)