This is the Dodge Challenger 2-Piece Driveshaft designed for 1000HP. This is a direct bolt in shaft with custom billet plates, which convert the rubber drives to 1350 U-Joints. We recently purchased a new balancer that can spin shafts up to 95000rpm. Most balancers only spin between 400rpm-3000rpm. We have found that after 5000 RPM, the slider in the middle becomes unstable. A slow speed machine would never catch this problem, or be able to correct it. Thankfully, we have had great success with fixing this problem by balancing the shaft at real speed. If your looking for a shaft that is just as smooth as the stock shaft but strong enough to withstand excessive horsepower, look no further.