Leaking pinion seal.As others have stated,top it off and it will be fine for a short time until you can get it fixed. It doesn't take much oil volume to make a mess like that. Make sure to replace it with a quality seal and you'll be set.
That's bad, right? How bad on a scale of 1-10, 10 being that my xk might not run tomorrow.
I didn't hit anything, and I didn't hear anything break.. and it's not dripping, etc.
I don't know how long it has been like this, but I don't think it was like this a month ago but I'm not sure.
Could it just be the seal or something?
Agree with above about the leak, but if you have the QD II system with the
ELSD's , i would fix it asap as you will be loosing the expensive friction modifier as well .Don't know how much you pay for fluids there , but here for the price of 1 bottle of friction modifier and 1 qt of syn lube ,I could prob. pay to have a garage change the seal . Just my .02
I'm gonna agree it's a bad pinion seal. Being as you don't know for sure how long it's been like that I would first top off the diff fluid and then beat feet to get it fixed. You say you don't think it was like that a month ago but you aren't sure - your pumpkin could have been low for a while running hot and doing some premature wear on the gears inside.
Hopefully, and likely, all is well but I wouldn't drag my feet getting it taken care of.