OK I noticed something with this truck i own and i need help. I have a 14 inch lift. I noticed that the driver side bed sit a half inch lower than the passenger side. Everything looks good. I have a 4 inch block and 7 leave springs on each side(Identical). I was thinking that the gas tank is on the driver side. I don't know, i'm confused on what to think or do. I took it to a off-road shop and they told me to throw another leaf spring on the driver side. It just doesn't seem right.

 

tossing a few things out here how much Fuel you have in the tank its on drivers side. Is the ground level? and is the springs the same thickness some srprings are thicker then other side to compinsate for the fuel tank weight?
tossing some ideas at you. I put the front springs on wrong on my yota bomber many years ago rt side sagged cause it was shorter to make up for the DIFF

 

I ran into a problem like this once before and the lift company sent me a new leaf spring for the one side. I'd call what ever brand of lift you have and talk to one of there guys there and they will most likely just send you what you need to fix the truck, well they did for me at least.

 

How long has that lift been on the truck? I just now finally got to see a big picture i was looking at just the thumbnail. I didn't know to put the pointer on it and don't double chick it will enlarge it for you.
do what stanford said call them and see what they can do for you.
they may do something if its new if its been on there for years may not
wear and tear
hope the best for you
Pizzo