The sealing rings are synthetic resin with chamfered ends. Check the condition of the sealing rings, and replace them only if they are worn, distorted, or damaged.
For a better fit, squeeze sealing rings together slightly before installing them.

Apply ATF to the new sealing rings, then install them on the secondary shaft.

After installing the sealing rings, verify the following:
The rings are fully seated in the groove.
The rings are not twisted.
The chamfered ends of the rings are properly joined.
A/T Differential Backlash Inspection (A/T)
Install the driveshaft and intermediate shaft into the differential
assembly, and place the axles on V-blocks (A).
Measure the backlash of the pinion gears (B) wit ...
Special Tools Required
Mainshaft Holder 07GAB-PF50101
Remove the bolts securing the ATF inlet line (D) and ATF filter holder
(E), the line bolt and sealing washers, and remove the ATF inlet line, ATF
hose, ...
Adding Engine Oil
Unscrew and remove the engine oil fill cap on the valve cover. Pour in the oil
slowly and carefully so you do not spill any. Clean up any spills immediately. Spilled
oil could damage components ...