Or are you saying there was something that actually broke? The housing or the side bearing on the diff disintegrated?
There is an oil seal on the side, should be part number 90311-47012 (it often leaks so I've replaced it a couple of times). Maybe that just came apart? This is common because the right side axle is not well supported on non-ADD trucks and can wobble, particularly if the c-clip is broken and the axle can move more than normal. IIRC it should be about $10 from Toyota.
If it's just the seal, it's not a difficult repair. Getting at it is tougher, particularly with the diff still on the truck.
If it's something in the diff itself and you are running stock you can get front diffs for nothing usually. Even built ones aren't worth much. I ended up selling my front Air Locker + 5.29 diff for I think $250. I got the stock open + 4.10 for a 12 pack of Coors Light.
FWIW, these photos still show the studs pressed in. I just use bolts now so it's much easier to R&R CV axles, especially the right side one.