Came axross somting i havent seen yet the nut that holds the berrings on the pinion backed off alowing the pinion to go to deep into crown and interferd and smoked the pinion teeth right off. Have rebuilt many front diffs but have never seen thiss nut come loose see somting new evry day fixen subarus

Wow, that's a new one. I've also seen the bolts on the crown back out of the carrier and get chewed up inside the rear diff on a '05 Legacy.

The lock nut on the end of the pinion shaft backed off? Could have a seized thrust bearing that spun it off?

not on the awd end on the pinion end the nut that holds the two berrings in place berrings did not fail just came loose was very strange have never seen thiss one. Tranny had never been apart.