+1 springs sag big time after a few thousand miles. 1" difference wouldn't be at all surprising.
I can add to this, I had a set of Falcon shocks put on my Rebel a few months ago.
When new? The rears were a scunch over 40in to the rear fenders, the front right was 39in flat, the front left I think was a scunch under 39.
Now the front driver's side is about 38.5in, the front right is 38.625
The rear driver's side is like 39.5in, the right rear is about 39.75in.
(On a Ram, both the driver
and the big fuel tank are basically on the driver's side)
Full tank of gas IIRC, ground might not have been totally level, but it was the same spot I've done all my measurements in.
I know some say that a shock doesn't effect the height of the vehicle and all that, the measurements I did with my truck say otherwise.
The addition of the falcon shocks alone (set to medium) raised my truck about .75-.8inches in the front.
On a new truck you're looking at fresh (tallest) tires, fresh shocks,
and fresh springs.
It is the truck's "maximum" height in that configuration.