Alright, so I own an 89 Formula 350 it has the 3.27 posi rear end. I was driving the other day and went to make a turn and started to rear a humming or rumble coming from the rear. I pulled over and the differential had a small hole and all the oil was sprayed out onto the muffler and the road. I took it easy on the way home, drove fine but made a noise on and off. Took the cover off after i got home, only a short drive and it look good but after feeling around i found 3 chunks of metal that used to be a bolt. Check the pictures and you can see where it came from. I have no clue how it worked its way out, with no prior signs or noises. Have you even heard of this? Its an original rear, never rebuilt. Looks like it was it great shape, and looks like it is now. Do I need it rebuilt, or should I get a used one? Thanks for any input.
Chris
https://i.imgur.com/510hu.jpg
https://i.imgur.com/DV4ec.jpg

 

replace with a fastener and some loctite to keep it in place and see what happens.

 

I cleaned it out and closed the end back up just so i can pull it in and out of the garage during the winter. But in the long run, after those gears chewed up that bolt will everything start to wear down faster? I would rather fix it now than have even bigger problems later.

 

Nothing is going "to wear down faster". If you replaced the bolt and inspected the gears for damage and replaced the fluid you should be good to go.
If you did NONE of the above, who knows.