PMD Products Shifter Seal fits GM Transmission Turbo 350 400 425 700-R4 TH200 TH325 4L60 4L80E 6L80E AT540 MT640 Seal is mandatory to stop the fluid leakage around the shifter selector shaft mechanism through the transmission case. Fits GM 200, 200C, 200-4R TURBO 350, 350C TURBO 400, 425, 475 GM 700-R4 GM 4L60 4L65E 4L70E 4L80E 4L85E 6L45E 6L50E 6L80E 6L90E 8L90E Fits Allison AT540 AT542 AT543 AT545 AT1545 MT640 MT643 MT644 MT647 MT650 LCT1000 LCT2000 LT2400 metal clad shifter gear selector rod seal , 0.752 inch outside X 0.501 inch inside diameter. Transmission only requires 1 seal