Rear Diff leaking around fill plug

Hey guys I did the search and can't find the part # for the rear diff fill plug crush washer. I'm guessing thats what is wrong, all the sudden its leaking around the fill plug. Can anyone give any other opinions on what it might be? But most of all give me the part # for the crush washer and fill plug #'s Thanks

'05 with 120k 4x4

 

Thanks bud, I'm wondering if its too full? Kind of weird its coming out of the fill plug. And I changed it around a year ago and no issues till now

 

Well its in my garage, level as can be. I just noticed it start leaking about 4-5 days ago. its very minimal, but it is def coming out of the fill plug

 

Doesn't really have a color that I can tell because its just damp around the plug and below it, but not even enough to drip

 

Must be a washer, I have tighten it since I saw it and its tight. Thanks for your help man!