self-leveling rear suspension

Ok so I have a 2006 SE6 without air suspension. I would like to add this for when we tow a heavy tent trailer. What are my options? Does anyone have a diagram? does it have its own compressor? etc..... Thanks

I don't think you want to go OEM, too expensive........

You could have a "manual" setup.....same setup, just no compressor....lines go to a schraeder fitting......use a portable air compressor to pump them up......

Only problem with this setup is, you will have to check your level evey so often for proper height......

Details that many folks forget.... The mini-GM vans are rated to pull a MAX 3,500 lbs. This assumes only 150 lbs driver, on flat ground and with a calm wind. If you also add more weight (other folks &/or rear cargo) into the mini-van, its MAX towing weight goes down. For example, if 3 x 200 lb people also in the van, then its max towing weight would be 3,500 - 600 lbs = 2,900 lbs. If you tow up hills, against strong head wind or other "stress" (like stop/go lights in a city), then subtract even more towing weight. For example, 500 lbs of "environment stress". Thus, max towing weight is now 2,900 lbs - 500 lbs of drag = 2,400 lbs "MAX". Yes. One can pull more trailer weight but its "over taxing" its transmission, engine and its FWD system. If wondering, I only pull max 3,000 lbs with empty mini-van and only me inside the vehicle. And, I avoid the steep hills as well. And, my mini-van has an aux ATF cooler for attached 5,000 lbs trailer as well. And, my 3,600 lbs axle trailer has its own electric brakes. IMO, all mandatory vehicle / trailer upgrades. Especially when pulling more then 1,500 lbs - behind the GM mini-vans.

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Regarding "improving" rear suspension (for trailer tongue weight support or internal cargo weight), there are 2 different non-GM products I would recommend. They are:
Timbren SES - Rubber blocks. re: http://www.timbren.com/ses-van-suv.htm & http://www.timbren.com/timbren-application-guides/application-pdfs/GMRAZT.pdf
Firestone / Ride Rite Air Bags re: http://www.firestoneip.com/RideRite/kitSearch.aspx
Note: Firestone are adjustable (manual or compressor) and Timbren SES units are an "install it and leave it" solution.

If wondering, I purchased / installed Timbren SES units within my 2009 Montana van. I purposely installed Timbren SES units instead of going with factory self-leveling system (that use air shocks and have high risk of long term problems). For pictures of my vehicle's Timbren SES units (which are installed inside the factory coil springs), surf:
http://i178.photobucket.com/albums/w251/Spike99-Pictures/Montana%20Van/TimbrenBottomOutsStop-3.jpg
http://i178.photobucket.com/albums/w251/Spike99-Pictures/Montana%20Van/TimbrenBottomOutsStop-1.jpg

Also.... If your trailer can accept a WDS system, do install one. Even a mini-WDS system (for 300-500 lbs tonque weight trailers) is a good thing to install. And yes, Timbren SES units and mini-WDS system can be used together. WDS is made to transfer most of the trailer tongue weight to the front of the Tow Vehicle. Thus, allowing more FWD traction as well. If unable to connect a mini-WDS to your attached trailer, ask your local welding shops if they can "make it fit". re: Weld chain clips on the trailer's tongue. Very easy weld job - for a professional welder.

If wondering, I would install Timbren SES units on other Tow Vehicles again. Without hesitation. Once installed (and yes, they are a DIY install), they do work when needed. More rear end down compression, the more up support they provide. And best of all, Timbren SES units do NOT impact empty ride comfort. No worry about air leaks and/or constant adjusting air pressure (like air bags). My next Tow Vehicle will use Timbren SES units as well. If wondering, my previous Tow Vehicle had Timbren SES units (coil spring version), and it worked great of that older vehicle as well....

If going with Timbren SES units, do shop around. Some places charge double the price. And, some places charge shipping as well. If a DIY person, one can install them using instructions within http://www.timbren.com/timbren-application-guides/application-pdfs/GMRAZT.pdf Think I paid $79 for 2 x rear Timbren SES units and installed them myself. Much less cost than factory self-leveling system, that break down in time.

Hope this helps in your heavy hauling / towing research.....