Do you have a spacer/coilover lift up front? I was under the impression that the 63" chevy spring swap lifted the rear around 5 inches over stock, that is the only thing that is keeping me from swapping them onto my Taco. If you search past posts, it seems that the 63" chevy springs give more lift than you can make up for in the front without a suspension lift via drop brackets like the Trailmaster and fabtech lifts do.