just pull off the bottom pulley, or, harmonic balancer as its called. Sleeve goes over its shaft. New seal drivin into the oil pump housing, and your done. Nothing more required than loosening your belts, walking off the harmonic balancer, installing sleeve, remove old seal, replace new seal, install harmonic balancer, tighten belts.

No need to go inside the timing cover at all.

85 4Runner - With NEW Marlin 4.7 Gears!! It's a whole new beast!