Dana 50 30 Spline Ected Max Selectable Locker For Use With 30 Spline Axles;For Use With All Ratios; Able To Shift From Limited Slip To Spool On The Fly; No Additional Parts Needed;Smooth Street Operation;4 Year Replacement Warranty FORD F-250 F-350 BASE CUSTOM SUPER CAB XL 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 4.9L (300) 4.9L LPG (300) 5L (302) 6.6L (400) 6.9L Diesel (420) 7.3L Turbocharged Diesel (445) 7.5L (460) DIESEL GAS LPG Auburn Gear Auburn Gear Dana 50 30 Spline Ected Max Selectable Locker - 545020 545020 Differentials