I was following a very slight oil leak for a while and sourced it to the valve cover gaskets. As these leak it tends to travel down the backside of the engine. I was noticing it collecting on the bottom of the bell housing, on the front skid plate, and even the steering rack boots.
I used toyota parts and replaced the valve cover gaskets, spark plug seals, half moons, cam plugs, and finished with new washer gaskets.
Not knowing the maintenance history I was nervous about what I might find under the covers. Luckily it was this:
Notice the tape around the plastic wire loom cover. As others have mentioned in the past, this is a must do. Sure enough they wanted to shatter into a million pieces. This saved said pieces from falling into the heads.