There have been a plethora of threads recently about how to do a 2" lift, install shackels, shocks, etc. (yes, my own included). As a service to future searchers, I thought that I would compile all of the information that I have found on the subject. Maybe we can make this a sticky to deter some more duplicate threads?
Summary: The basic 2" lift is done with a torsion bar adjustment on the front, and either lift shackles or an add-a-leaf on the back.
Torsion bar adjustment: The torsion bar adjustment is done by turning the torsion bar adjustment bolts. For most people a 2" lift would be about 7-8 turns. It will be much easier to turn the bolts if you jack your truck up by the frame to take the weight off of the suspension. Measure each side of the truck to make sure they are the same height after the adjustment. You will need to have your alignment checked after adjusting the torsion bars. Here are pictures of the bolt from the following thread http://www.coloradofans.com/viewtopic.php?t=893
Shackles: The leaf springs are attached at the back with a shackle. This shackle attaches the spring to the truck frame and allows the spring to flex. A lift shackle is about 4" longer than the stock shackle, giving you 2" of lift at the axle. To replace your shackles, lift your truck by the frame to take the weight off of the springs. Then unbolt the stock shackles and remove them. To install the new shackles, adjust the height of the truck to line up the holes and bolt the new ones in.
Aftermarket lift shackles are available from AIM Industries (http://www.truckn-store.com/product....t.asp&ID=98017
) for $99. The picture on their website is a generic picture. The actual shackle from them looks like this:
The other company offering shackles is Synergy Offroad. Their website is http://www.synergyoffroad.com/gmt355shackles.html
. Their shackles are $55. I haven't seen any pictures of their shackles on a Colorado yet, but they look high quality.
Shocks: When you lift your truck, you are at risk for overextending your stock shocks and blowing them out. The right thing to do is replace your shocks. The correct Rancho shocks are 5300 (or equivalent) for the front and 5190 (or equivalent) for the rear. The shocks should be a simple bolt-in installation.
If I have left anything out or got something wrong, please let me know. Hope this helps some people out.