Just found this...so I guess you're correct to be disappointed, if these numbers are accurate (found on AOL Autos):
2010 Avalanche Specs:
LS 4x2
Options
LT1 4x2
Options
LTZ 4x2
Options
LS 4x4
Options
LT1 4x4
Options
LTZ 4x4
Options
Base engine size 5.3 liters 5.3 liters 5.3 liters 5.3 liters 5.3 liters 5.3 liters
Base engine type V-8 V-8 V-8 V-8 V-8 V-8
Horsepower 320 hp 320 hp 320 hp 320 hp 320 hp 320 hp
Horsepower rpm 5,400 5,400 5,400 5,400 5,400 5,400
Torque 335 lb-ft. 335 lb-ft. 335 lb-ft. 335 lb-ft. 335 lb-ft. 335 lb-ft.
Torque rpm 4,000 4,000 4,000 4,000 4,000 4,000
Payload 1,333 lbs. 1,333 lbs. 1,333 lbs. 1,433 lbs. 1,433 lbs. 1,433 lbs.
Maximum towing capacity 5,100 lbs. 5,100 lbs. 5,100 lbs. 5,400 lbs. 5,400 lbs. 5,400 lbs.
Drive type rear-wheel rear-wheel rear-wheel four-wheel
That said...I agree wholeheartedly with GoNavy429...AND when I was looking at the options on Chevy's website, I believe the HD Trailering package HAD to be ordered with the oil cooler and other things, so I believe you're set.
This is what throws me about yours having 3.08 gears....this is straight from Chevy's website:
# Trailering Package:
Trailering Package, heavy-duty - includes 3.42 rear axle ratio, 2-speed active transfer case, external transmission oil cooler and engine oil cooler, provides increased trailering capabilities. Included with Texas Edition and Regional Value Package.