2500hd

Maybe I'm looking in the wrong places. But I just bought a 2013 2500HD Crew Cab 2 wheel drive to replace my 2009 1500 xcab. I lowered my 2009 2/4 so it was easier to work out of. Now I really need to lower my new one as it is a 2500HD. Any suggestions???

My boyfriend has a 2005 GMC Sierra 2500HD extended cab long bed truck and I found a canopy deal, but want to make sure it will fit. The measurement on our truck is 68" wide by 8'4" long (outside) and the canopy I'm looking at says 68" wide by 8' long. Will this fit? Is my truck really considered...