The EAT912A585 fits a Dana 30 for a 3.73 and numerically higher gear ratio. The 2012 Ford Expedition has a 8.8” high pinion front end with 31 spline axles. 4Wheelparts offers the following traction devices for this front diff: ARBRD81 Air Locker, EAT19605-010 clutch type limited slip, YKGYDGF8.8-31-1 clutch type Limited slip. The rear end could be a 10 bolt Ford 8.8 or a 12 bolt 9.75. For the 8.8” 31 spline IRS differential a Eaton 913A561 Trutrac would be an excellent choice.
If you have the 12 bolt IRS differential then a EAT913A477 Trutrac would be an excellent choice.