ARB RD136 - Manual (Page 15)

3 Installing the Air Locker
13
3.3.2 B High-Pinion Differentials
Mark a spot on the inside of the differential housing on the ring gear
side in the position shown. (Fig.6.) Ensure that the hole will be clear
of the rib on the outside.
NOTE : This position has been chosen to ensure that the airline
and bulkhead fitting clear the factory suspension
mounts.
Figure 7.
Cover the drive pinion area with a rag to protect it from metal filings.
Secure the differential housing to the work bench.
Drill an 11.2mm [7/16”] diameter hole through the differential
housing square to the inside surface.
Tap the hole from the outside using ¼”NPT thread tap.
Remove any sharp edges that may chip off from around the hole
and fall into the housing.
Very carefully, remove the rags and inspect with a service light
inside the housing to insure no metal filings are left behind.