Trucks can vary 1in or 1.5in stock. Some have alot of nose down and some are barely nose down. Plus shocks sag, so if you have an 04 and they have 07's your shocks should have settled more.

Also a 3in Body + a level will be about the same size as a 6in, it will actually be .5in taller in the rear.

 

me and my bro bout our trucks brand new from the dealer with the lifts already on. Its weird right that theres is a little taller. i hate it

 

Shocks have nothing to do with ride height. Springs affect ride height.