New springs - still got a lean!!!

You may find nothing wrong after you check everything. Half an inch doesnt surprise me. Bet my car is off by at least that.

 

The gas tank is very offset to the driver's side that puts more weight on that side.

May not seem like a lot but gasoline weighs at 6lbs per gallon. Half a tank is right at 60lbs.

Full tank is 120lbs.

And by this response sounds like very good reason for the sag:

The cool thing is that it's testable. With half a tank put 60lbs(or 30lbs if it's 1/4 full,etc..) on the passenger side trunk side. Then re-measure.

Another variable is the floor, put a level down and measure it to see if it's level. concrete sinks over the years.
if it is level you can use it to test it to see if it is your wheels/tires.

Put the car on jack stands and measure them first to see if they're level, remove wheel/tires and measure to the center of the dust cap(axle center thing I don't know what the tech name for it is.)

 

Centerline of axle?

 

I think its the nature of these cars. Someone else may verify.
Mine is 5/8" offset on the same side, thats with taller shackles, 4 door body, and the 4 leaf setup.

 

I remember our previous Mav sat dead even side-to-side - BUT to be fair that car was built by a very qualified, lifelong Ford guy and racer, AND it did have an 8 gal. fuel cell centered perfectly in the trunk. I don't know why silly little things like this bug me. Oh well...