Your server might come with one of two sets of rackmounting hardware. These are:
Standard
Universal
If you are unsure what rackmounting hardware you have, see Unpacking the Server and Identifying the Rack Mounting Hardware in Sun Server X2-8 (formerly Sun Fire X4800 M2) Installation Guide.
The documentation set includes two documents that provide instructions for installing the rackmounting hardware:
Installation Guide (online only)
The Sun Server X2-8 (formerly Sun Fire X4800 M2) Installation Guide describes how to install both the universal and the standard rackmounting hardware.
Rackmounting Hardware Installation Guide (printed and online)
The Sun Server X2-8 (formerly Sun Fire X4800 M2) Rackmounting Hardware Installation Guide describes how to install both the universal and the standard rackmounting hardware.