Late to the party, but I have the same issue and did a lot of research on it. What I've learned is that it is "normal" for the driver's side to be lower than the passenger side. When these trucks were designed, they put all of the heavier components on the driver's side for some strange reason (mostly organization and production costs, but the jury is still out on that one). You've got the steering setup, the fuel tank, the battery, and the driver all lined up in essentially a straight line. Overtime, as you can see, wears on the suspension and causes the driver's side to dip below the passenger side.
Back in the day when these trucks were rolling off the factory floor, it was possible to take them to a dealer and have them install a certain coil spring to essentially level out the imbalance. However, these springs are long forgotten and people have taken to other means of aesthetic balancing. I haven't found a 100% fix for the problem, but I do want to let you know that a few people have cut their passenger side coils in an attempt to balance it out. This has worked for some, but not all of those who did it. I've even read where an individual installed brand new N02 shocks, but it didn't solve the problem.
If I find a permanent fix, I'll report back.