Have 5:29 gears with a Detroit locker. I just changed the gear oil and the drain plug was covered with metal some chunks too. What would cause this and how can I prevent it. It is my daily driver too. Maybe that's why??

 

Who set up the gears? If they were setup and broken in properly, there should not be chunks of metal in the oil. Some metal "sludge" on the plug is to be expected, but definitely not a lot, and not chunks. You might want to pull the 3rd member and check the ring & pinion for visible damage. Any strange noises? Not really much you can do beside making sure the gears are setup properly, and following proper break in procedure. Obviously you want to have a quality oil in there, but for most normal uses, unless you're using something really odd, gear oil is gear oil is gear oil.

 

Agree with all of the above. Absolutely pull the 3rd and see whats going on. Define "chunks of metal" did they look like bearings or gear teeth? locker pin or spring maybe?

 

In the same boat right now. 5.29 gears put in over a year ago. Had a noise under load, but nothing coasting. Some metal on the plug. Pulled the 3rd and the pinion was chunked apart. No pinion bearing preload, and can turn the carrier adjusters with my fingers. Definitely not setup correctly.

 

More like shards of metal about 1/4" long I bought it used and when I installed the 3rd it looked fine. I use the correct gear oil . When I'm at a stop and I go to let the clutch out just a little I sometimes hear a thud. I'm sure it's the rear end but I'm not sure what's causing it

 

That thud is most likely the locker engaging.

Metal shavings are okay and normal.
Metal chunks are not okay.

 

takes 45-60 minutes to pull the third...pull and examine it