Alot of trucks, if not all of them, sit higher on the pass side. It becomes more noticable when you drop it. The reason I suspected is because of the years of compressing and uncompressing on the driver-side body mounts due to the forces of accelerating. (Notice your truck lifts up on the driver side when you accelerate)
IF you follow the instructions by mounting the sway on the pass side of the links with the correct spacer, you'll be ok from that point of view and it will clear the ph bar. As for the ride height difference, I bet it's still there when you're done.
As for needing a new one, I doubt you will from what I can see.
Ya, hate the dreaded lean!! Also think it's contributed to gas tank alot too, as well as most people drive alone,and most people take right turns fast ie. compressing springs, shocks, and body mounts constantly, along with what BOSS said.