[acammer]

Eaton actually references this on their website somewhere, the TruTrac is expected to have more substantial lash than a standard differential. I think they said something like 4* on the output side is expected. That's quite a bit on a 28" diameter wheel. Add in all the other parts lash (clutch, transmission, 2pc driveshaft, ring and pinion, axle at each end, and you end up with a pretty substantial amount of lash.

As long as it's quiet and working right, I wouldn't be nervous. The very dark oil on the initial change is perfectly normal, that's the coating wearing off the ring and pinion as it breaks in, and is a large part of the reason you make the early 500 mile oil change on a new ring and pinion, the oil will look much better on subsequent changes.

Also keep in mind that Eaton recommends NON-synthetic fluid, and NO limited slip additive - those are both OPPOSITE of what the factory original calls for.