That usually happens when the nut comes loose, it marks the carrier.
I've known someone who just tightened the nut, flushed it out and was fine. This was on a second gen.
To do it right you'd need to take the pinion out and install a new crush collar, check/replace bearings, flush everything including the axle tubes, install new seals, and reassemble with a new pinion nut.
To take your chances you could put in a new seal, install a pinion nut with red loctite, and torque it to get the proper bearing preload. And maybe stake the nut in place.
If it makes no noise after that you're ok. If it makes noise you're out the money for the nut, seal, and oil.
Take your pick. I'm not recommending one or the other.