How close is it are they to being level? And is that with the vehicle at normal ride height? The front being higher by say 1/2 : 3/4 of an inch is what I would believe to be within tolerance.

If you're 3" different from 1 end to the other, then I'd search for a way to lower the mounts up front and / or raise the axle mounts. fwiw/imho/point 02/etc..