so as I'm finishing the install of my new cat back exhaust , (purch. from AB on sale $ 269) and swearing at the fit...I notice gear lube starting to drip from the input shaft on the rear diff. thats GOOD news 'cuz that means there's still oil in it !! so I've prepared myself for replacing the seal and befor I actually order one I thought I should check the vent line....it was clear but the banjo bolt and vent nipple were corroded solid !! took it out and ran a drill through both to clear them out....pretty easy fix......I actually heard the air vent out as i removed the bolt...that should cure the leak
but here's a reminder to check these now and then !!

 

That's a great tip. Thanks for bringing that up.