Side Retainer

Install bearing outer race to side retainer.
Install a new oil seal using the ST and hammer.
ST 18675AA000 DIFFERENTIAL SIDE OIL SEAL INSTALLER

Fig 1: Installing Oil Seal Using Special Tool
Courtesy of SUBARU OF AMERICA, INC.
Apply gear oil to new O-ring and install it.

Fig 2: Applying Gear Oil To New O-Ring
Courtesy of SUBARU OF AMERICA, INC.