Sonnax heavy duty spring retainer kit GM-RS-3HPK includes a shim to help better support the springs and rolls. This is a drop-in replacement for use in stock or high-end diesel converters. The retainer features 10 sites of larger surface area contact with the stator cam, an improvement over the two smaller contact sites on the OE retainer. Greater surface contact enables the Sonnax spring retainer to prevent the common problems of bent or damaged retainers, providing enhanced wear resistance and durability.