This is the seal that seals the hub to the spindle from the Currie Performance & Raptor/F-150 full floater kits.
Seal Cross-Reference
High-performance non-synthetic racing 85W-140, gear oil meets the API GL-6 specification designed specifically for the requirements of 9-inch gear assemblies. It provides maximum shear stability and extreme pressure protection required to extend the life of your Currie rearend.