Thanks for the welcome porcupine73!
You're right about the Subaru rebuilds.....Expensive! The used trans and rear diff is a good option for us also but, since the entire drivetrain/diff combo also appears to be a scarce item, I think my son and I will start with taking a shot at this front diff and transmission. So far, I'm very impressed with the quality of the design, parts and materials on this Subaru Outback. My brother got 171,000 hard-driven miles (he put this horse up wet many times!) without ever thinking about gear oil.
Thanks again for the reply!