There are small tags bolted to the diff. Well, there was when it was built. Mine are still there. They will have series of ID #s stamped on them. {4.10, 3.55, ect} Being 4x4 mine says 3.55 on the rear and 3.54 on the front axle. If yours has 4.11 on the rear it may be 4.10 on the front. I think...