ARB RD145 - Manual (Page 14)

3 Installing the Air Locker
12
3.4 Drilling and Tapping the Bulkhead Port
An airline port must be drilled and tapped through the axle housing
casting to mount the bulkhead fitting into.
Cover the worm gear area with rags to protect from metal filings.
Mark a spot on the axle housing casting in the position shown in
Figure 7.
Figure 7.
Drill through the housing square to the inside surface using a
11.2mm [7/16”] drill.
Tap the hole from the outside using a ¼” NPT pipe tap.
Remove any sharp edges from the hole that may chip-off and fall
into the housing.