I think I remember a wiring diagram and directions for doing just that in a recent past issue of the TDR. I'll have to do some checking. It would have been within the last three issues.
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99' Quad Cab, 4x4, Auto, 3. 55, All options except fog lights and leather, Glasstite topper, Chrome Nerf Bars, VA CPC, DiPricol EGT & Boost Gauges Pillar Mount, K&N Air Filter, Turbo Silencer Ring Removed, Infinity sound w/pillar tweeters, 300w speaker system under rear seat, Metalic Red