Here is an image on what the diff looks like on the drivers side. Is it normal? Should it still be this dark? I cleaned off as much as I could with brake cleaner but it just keeps making the paper towel black with very little visible progress.




This is what the passenger side looks like.

 

It's fine. I wouldn't give it another thought unless you notice it start to drip on your driveway. They did put a new plug in for you, right?

 

I honestly didn't check for a new plug. I kinda just assumed. They did put in new bolts (all of them) and they guy said he had a box of plugs and would just put in a new one.