Does anyone know why?

[terrellautosports]

can anyone tell me what might be causing my wifes truck to be lower on one side? is the shocks bad? look at the rear fender wells over the tires. you can see a difference and really see it when it is on a flat surface.
also by looking at it can someone tell me what they might think, how much has it been lowered in front and rear?
do i need to pull out springs and see? are springs usually marked what they are? drop wise.

thanks in advanced.