Just wants a god clean up and service. That isn't the end of the World. I would clean and degrease then blast it off with brake cleaner so that it's not contaminated. Adjust it all up properly and it should be fine. Generally they get clagged up but are not greasy like that so they rust and stop moving. But being rather oily like yours might be a good thing.
There are no real mysteries in there. The bell crank pin is the bit that wears and give you problems. But inside should be fine.
I don't think that its EP90 but it may be bearing grease I'm not sure how it all works behind there Surely there's an oil seal between the inside face of the bearing & the diff to keep the EP90 away from the bearing then the bearing packed with grease thyen another seal to keep the bearing grease away from the brake parts & the elements away from the bearing Am I correct so worst ways this is bearing grease & I may need an outer seal
Hmm, there are pics on here somewhere from when I did mine.
Essentially, the half shaft, and hub are all one unit. OK they come apart with tools and knowledge, but if you think of the shaft and hub as a cork, then you are not far wrong. There is a shoulder on there which fits into the axle with an O ring to stop the inside leaking out. I don't think (from memory) that the diff oil can actually get into the inside of the brake drum. It can leak down the back of the backing plate and maybe then find its way in, but it can't ooze out of the axle straight into the bearing. I shall be back in an edit if I can find the pics / link