I am going to get the C5Z up on jackstands today & get a look underneath see what's going on w/ my diff. I started noticing a couple oil stain droplets here & there in my garage this past summer, got underneath as best I could when I was changing oil & had it partially lifted & did notice more weeping/mess on the diff/tranny cover. Never had an issue previously, no whining or grinding coming from the rear end, I swapped out the fluid around 2 years ago w/ Amsoil 75w90 prior to putting it away for the winter @ 30k miles & now the car has 40k miles - I didn't notice anything until the last few months.

I ordered some more Amsoil tranny/diff fluid expecting to swap it out again in the next few weeks, but figured I should determine whats going on w/ the diff before I do that.

I know there's also a chance it could be coming out of the overfill hole or something as well? Just want to know if there's any way to make certain its the issue w/ the sealant/gasket & not something else.

The fix is pretty tediuous since it involves dropping the cradle etc.

 

 

Not sure if this helps, but 1st picture is driver side, 2nd picture is the passenger side, as far as I know most all of the leaky butts were from the driver side axle seal. My car had low mileage when I did the repair around 8000 + miles & car was clean so it was easy to spot, & I had 2 instances where I found drops of diff lube on the floor. 2 summers of driving after the fix & driver side cover is still clean.

Also it is not necessary to drop the cradle to do the cover fix, but the exhaust has to be removed to get the cover off.

I was installing drop spindles on my car at the time of the fix so all the rear suspension was removed which made it easier to do the fix.

 

Well upon closer inspection I think I'm lucky in that it ISNT the driver side gasket/cover, I'm fairly certain its the vent & that fluid had been dripping a little @ a time for quite a while. Luckily seemed to be plenty of fluid still in the diff, I checked by poking my finger in there & actually even got a couple decent pics of the inside through the filler hole w/ my phone. See pics let me know what you guys think....judging by the fact the only place I could find "fresh" wet fluid was from the vent that's why I don't see the cover/gasket being the culprit.