[NiftySVX]

I would replace the seals while you have it out, that's pretty much standard procedure. It's really piece of mind because if the oil leaks out it will toast the diff and it only holds like 3/4 of a qt, so it might leak enough out to damage it before you noticed. Make sure and put wheel bearing grease on the seal lips so they don't stick, if the new ones don't come pre greased or you reuse the old ones. Also, check the inner joint cup for wear where the seal lip contacts the sealing surface. If there is any groove worn in it you will need to either replace that inner cup or simply install the oil seal at a different depth so the seal doesn't ride in the groove. Also, check for this same groove on the outer cups as this can cause water to leak in and take your wheel bearings. This was common on the first generation legacys. As for oil, the manual calls for 75/90. Also, it is reccomended that you use some liquid gasket on the threads of the drain plugs, but this is rarely done in practice.