I had airbags with an on-board air compressor on a previous truck. I currently have Timbrens on my 2001 2500HD duramax, they are much easier, a passive suspension upgrade that only comes into play when the trailer is connected to the truck. I've had mine on the truck for 5 or 6 years and during that time I've pulled the Bighorn and the ALFA Sun I owned before the 3055 10's of thousands of miles. They still look and perform like new.
Timbrens replace the bump stops on the rear axle. Installation is very easy, remove the bump stops and bolt the Timbrens in place of them. They don't change the ride of the truck when it is unloaded since the axle must be displaced ~ 3/4 inch before it contacts the Timbrens. With the extra weight of the pin on the rear axle the gap is closed and the Timbrens do there thing. That's it--install them and the work is done.
They are available online from truckspring.com.
Chuck Keskimaki
New 2010 3055RL Bighorn
Old 2001 Chevrolet 2500HD D/A Longbed, BD exhaust brake (115K+ miles, half pulling 5er's all over North America.