I have the same problem getting my Chevy dually pick-up worked on. For instance, many alignment shops don't have lifts / equipment big enough to do an alignment on a dual wheel vehicle. Many independent shops don't have a lift big enough to lift the truck. I usually go to heavy truck shops to get this kind of work done.
As for a dealer, you need to find a different dealer that sells Chevy commercial vehicles. Our local Chevy dealer sells work trucks up to the Chevy Silverado 6500 size. These medium duty trucks all have dual rear wheels and can be ordered with really long wheelbases. You must be dealing with a Chevy dealer who is not a commercial dealer.
