The following instructions describe how to assemble and attach the rear rack mounting assembly kit (sold separately) to the HPU:
Attach the rail adapters to the rear chasis brackets using the 10-32 x .5 screws from the kit. Note: the rack adapters have 4 screw holes to account for different rack depths but only two screws are required for secure assembly.
Attach the rear chasis brackets to the rear of the HPU using two 6-32 x .25 screws per bracket.
Use the remaining 10-32 x .5 screws to secure the HPU to the rear rails to a 19" rack enclosure.