Well... to conclude my highjacked thread, I figured it out. The angle on the middle u-joint of the drive axle had become too sharp (lowering transmission, lowering diff, while not lowering mid section). I spaced down that mid joint bracket and the noise stopped. Perhaps this is a problem I encountered only because my u-joint was already getting beat and the extra angle just exacerbated a pre-existing weakness. It might be a good idea though to space this bit down along with everything else for every 4" lift.