You will not have instability or side to side rocking with airbags on your 2005 GM D/A unless you go crazy with the bag's inflation. GM trucks do not have the issues other trucks have due to the airbags location and rear suspension design. Use approx 10 psi bag inflation for each 500 lbs you want to lift. like 50 psi for 2500 lbs. Never over inflate and deflate to between 5 and 10 psi when not carrying weight to maintain bag shape and have OEM ride.
First installed Air Lift Systems airbags in 1993 on our 1993 Chevy ext cab LB 4X4 to carry our TC and we dowve the truck 128,000 miles with about 100,000 with the TC on and twice to Alaska and all over the USA and Canada. Sold the truck to a farmer friend and it still has the same bags on with way over 300,000 miles on the truck as of last November. Never leaked either. Have them also on our 2004.5 Chevy 2500 D/A CC LB 4X4 truck and have over 149,000 on them now and they work perfect. We carry a heavy Lance 11'4" loaded with options and it's solid as a rock driving with 65 psi in the bags. About 40-45 psi when pulling our Carriage Carrilite 5th wheel that we are in right now in Florida.