I have a 2" level on my 07 nnbs. My factory axle went out so i replaced it with one from advance auto. 3 weeks later I noticed grease on my wheel and the outer boot was all kinked and twisted looking and slinging grease. Took it back they gave me another. Put it on and within a week that boot was looking kinked and twisted and a couple weeks after that it had a hole in it also. Never had a problem with other side. Only difference I see is factory boot has 6 ridges and new one has 4.