GM 6L45, 6L50, 6L80, 6L90 units may have TCC apply and release problems. Bore wear or a stuck converter feed limit valve can result in converter overheat, incorrect TCC apply or release, inadequate lube and cooling, and converter over-pressurization. Reaming the bore and installing the Sonnax oversized converter feed limit valve 104520-11 will restore proper valve function, resulting in proper TCC apply and release, regaining control of lube and cooling. Valve is hardcoat anodized to reduce wear Annular groove helps center the valve in bore Note Use of the VB-06 is required with the VB-FIX reaming fixture for this installation unless the stator support shaft is removed from the pump body.