ARB RD106 - Manual (Page 11)

2 Removing the Existing Differential
9
2.7 Use of the Thrust Block
IMPORTANT:
This model of Air Locker was manufactured to replace
Nissan differentials which employ either of the two distinctly
different methods of retaining the axle shafts.
1 Full Floating Axles
2 Semi-Floating Axles
Depending on which axle type you have, you may be required
to install the thrust block included with the Air Locker
kit before final assembly.
4.3.1 Full Floating Axles
Full-floating axles are completely supported and therefore do not
require a thrust block at all.
4.3.2 Semi-Floating Axles
Semi-floating axles are only retained inward at the wheel end of the
axle shaft and are supported in the center of the axle assembly by a
thrust block. You can easily identify this by looking through the axle
splines of your original differential carrier to see if a thrust block was
used.
If this is the case then you will have to insert the thrust block (supplied
with the Air Locker kit) into the differential center just before inserting
the Air Locker into the axle housing.
HINT : A wad of thick grease on the thrust block should keep
it from sliding around during installation.