The original power steering gearbox was still working after 85,000 miles but after researching the over boost problem decided to replace it with the new Delphi unit. My mechanic said the installation was straight forward and the enclosed directions with the gearbox were excellent. Steering is now more like a cross between power and manual. Road feel is much improved and I am very satisfied with how the car feels at both high and low speeds. The Chevelle also had recent steering and suspension component upgrades so it is about as good as it can be on the road.