I bought some "overload springs" from IPD for my 740 wagon. I'm having a couple of auto shop students install them, as it seems a pretty straightforward job. As they were trying to make the switch, they ran into problems with what they called the "bushings" at the top of the spring. The schematic directions from IPD shows two pieces that apparently attach above the conical metal piece at the top of the spring. On my car, these were deteriorated, apparently. My question, which IPD couldn't answer, is what these things are and, more importantly, whether I need special ones for the overload springs. I'd appreciate any help. Thanks