A little while back, I swapped my stock gears and carriers to yukons and truetracs. After a proper break in of 300 miles, I changed the lube and of course went back with a quality Valvoline 80W90. I guess I have 3k or less on them now, mixed highway, city, and wheeling time. For the heck of it, I decided to go ahead and change the lube again; just to make me feel better. I started with the front and when I drained the lube it was a nice golden color with minimal smell. Exactly what I expected. Filled her up and went to the back. That was a different story. The lube was darker brown and had the tell tale smell of burnt. Both front and rear had a small amount of metal shavings on the plugs as to be expected after a gear and carrier change.

With all that said, does it sound like things are ok, or do I have area for concern?

 

I did a change after my break in period as well. As for the next one who knows. I wouldn't worry about as it's a metal on metal kind of thing. You will always get some shavings. My front is always clean compared to the rear as it sees all the abuse and works the most. Unless you are having issues i wouldn't give it much thought. Try changing it again in 10k and see what happens.

 

Ok man, I appreciate the feed back.

 

IMO, I would pull the cover to visually look at gears to see if there is any unusual wear going on.
Assuming proper amount of gear oil was used...yes the oil in rear will generally be darker in my experience

 

I'll probably pull the cover next time around. I fill them like I've always filled a diff for the last 20 years. Drain, plug the bottom, fill from the top until I'm at the fill plug, give it a quick extra squirt to cover over flow and tighten it all down.

 

The front really isn't doing much unless you're in 4WD. The rear in normal driving has all the load. It's normal that it would see a darker oil. I run the heavier weight in the rear since I sometimes pull a trailer.