GM 6L45, 6L50, 6L80 and 6L90 units may exhibit multiple line pressure and cooler/converter/lube flow problems due to excess wear in the pressure regulator bore. Deterioration at the balance spool end allows critical fluid loss, resulting in high line pressure, harsh shifts and overheating due to reduced cooler/converter flow. Wear at the outboard spool robs converter feed pressure and lowers line pressure, resulting in soft shifts and burnt clutches. Installing Sonnax pressure regulator valve kit 104520-15K restores the hydraulic integrity of these circuits for proper line pressure control in all ranges. A new pressure regulator valve outer spring is also included to replace weakened original springs and provides a modest 5 psi increase across the pressure curve. Hardcoat anodized aluminum valve combats premature wear Lengthened critical spools operate in non-worn portion of bore for added stability and wear prevention Annular grooves help center valve in bore to reduce future side-load wear Replacement spring provides modest 5 psi line pressure increase No pump drilling required Drop-in Zip Valve™ parts install quickly and easily Note: Pump must be removed to install kit. This kit replaces the original Sonnax pressure regulator valve kit 104520-14K. If you have the discontinued regulator valve kit and need instructions, you can find them here. Contents Valve Spring Checkball