Going to guess here but are you saying that this seal is to keep oil from leaking out the splines and not from around the yoke? If so pull the yoke off and make sure that there is not a groove from the yoke seal, replace that seal while it is off and clean up the splines and yoke and threads of any oil and seal the end of the shaft at the washer and nut with RTV silicone and call it done.
By the way where in So Cal are you? I am in Bakersfield.