Ford 8.8in. IRS 31 Spline Ected Max Selectable Locker For Use With 31 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 LINCOLN MERCURY AVIATOR EXPEDITION EXPLORER MOUNTAINEER NAVIGATOR BASE CONVENIENCE EDDIE BAUER EL EDDIE BAUER EL KING RANCH EL LIMITED EL XLT FUNKMASTER FLEX EDITION KING RANCH LIMITED LUXURY PREMIER XLS XLT XLT SPORT 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2L (1999cc) EcoBoost 3.5L (3496cc) (Duratec) 4.6L (281) InTech 4.6L Triton (281) 4L (245) 5.4L Triton (330) GAS Auburn Gear Auburn Gear Ford 8.8in. IRS 31 Spline Ected Max Selectable Locker - 545005 545005 Differentials