Bed & cab not lining up

[ilovehockey44]

Okay so here it goes. I just got the truck last month, me being the third owner. It's got about 167K on it, and it's the 5.3L Vortech V8 extended cab with the 6ft bed. It is in very nice shape but there seem to be some minor things. The one that is really bothering me is that the bed isn't aligned with the cab. Previous owner put Cooper 33's and looks like a small body lift with a add a leaf kit. What could be some possible things to try to straighten her out? The passenger side seems aligned. The drivers though is about an inch lower.