From the GM order guide: HD Trailering Package includes (GU6) 3.42 Axle Ratio, (JL1) Trailerbrake controller, (Z85) Suspension Package and includes (NQH)transfer case, active, 2-speed with 4WD model
The HD cooling for oil and trans are listed as standard.
2015 Order GuideWhat transfer case do you have? I'm not sure if the 2-speed is more heavy duty?
Also, the Z85 suspension is higher rated, not sure how much, plus it has air load leveling. "Suspension Package, Standard, increased capacity, Premium SmoothRide with Air leveler 1 - Included and only available with (NHT) HD Trailering Package."