One of the first things I did to lower the rear of my pickup was to use the longer shackle kit from NoLimit. It didn't do much, less than an inch. The shackles can't be much longer than stock because the top of the shackle will hit the bottom side of the bed floor. Save your money don't invest in a dropped shackle kit. I did put mono leaf springs in the rear that lowered my pickup about 5 inches in back. With mono leaf springs you will have to buy a pair of really good shocks like QA-1 adjustable shocks. I think the best bang for the buck would be to flip the rear axle to above the springs but you will have to C notch the frame like Ogre did. Regardless of how you lower the rear you will have to C notch it.