Nope, that is a factory plug, they forgot to put the breather in, happens more than you think.
Axle vent, WTF?
On my 04 Titan, my stock axle vent looked like all the pictures I've seen. I recently bought an 05 and am getting ready to do the vent mod and I see what you're seeing in the attached picture. It's like the guy who owned it before me just put some sort of plug there. I'm about to pop it off and do the mod, but wow. Here's to hoping it doesn't blow up in my face.
