On a shadetree scale of 1-10, how hard is this to replace on a M119(500e)?

Mine is leaking, and from the location is starting to dribble the oil onto the crossover pipe behind it. I've heard that it needs to be replaced from the inside, dropping the pan, which I guess would give me a chance to check the guts of the block as well. But that seems a little extreme for just a sensor?

Thoughts?