When you use a GM pump with a Mustang II rack the steering is too sensitive so Speedway Motors offers a replacement valve to lower the boost of the GM pump. If someone (not me) is sharp on the workings of a p/s pump maybe they would know if a spring that goes behind the piston is available that would drop the pressure. This would be an easy fix and it wouldn't harm any of the original parts so the process could be reversed.
