MARK THE BARS RH & LH, AND ALSO F & R! These can be installed backwards (front to rear) and on opposite sides (right to left)...this happens often and if you reassemble them wrong, you cannot get the ride height adjusted properly.
Also...I never use an impact on t-bars. The rotation speed can heat up the threads and seize them into the nut (galling). If that happens...its torch-time (been there). GM installs the bolts dry (duh), and given their location under the truck...they get a lot of mud, sand, water, and such caked all over them. Its a good idea to clean the bolts before you attempt to un-thread them. A wire wheel on a drill and a liberal soaking with WD-40 will prevent the bolt from getting jammed-up, and it makes un-threading them much easier. If you feel the torque resistance increasing as you loosen the bolts...STOP. Let them cool down, and apply more WD-40 and work the bolt back & forth a few times. This is why I do them by hand...so you can "feel" the fastener starting to seize and stop before you destroy something. C-clamps also help...they take the strain off the threads. The threads are designed to "hold" the proper ride-height....not to "pull" the vehicle into proper ride-height. There is a specific tool called a Torsion Bar Clamp that you can use but its really nothing more than a C-clamp. Its not mandatory but, it does help by removing all the load off the threads while you are turning the bolts.
When you re-assemble them, put a glob of grease on the threads. This will keep the bolts cool during the tightening and prevent galling. Also put another glob in the cradles...to keep the creaks and groans to minimum when you flex the suspension. I find that its more accurate to make your final height adjustment from the high-side down. So I over-crank to say 24"...then I flex & bounce the suspension...then un-thread the bolts to arrive at the desired height. Flex & bounce again...then re-measure...then call it a day. I shoot for +/- 1/4" side-to-side...anything smaller than that and you end up chasing your tail. The H3 is very weight sensitive. Fuel, tools, or fat-girlfriends, etc....all effect the ride-height. It will magically change every time you check it...so don't be too concerned if you cannot get it closer than 1/4".
