hey i got a 2006 chevy z71 and i never have had any real problems with it besides the rear u joint went out, it has about 130000 miles on it but last night when i was in 4 wheel drive the front end was kinda makin a grinding noise, not when i was easing along but when i went to get on it a lil bit, but it seemed to be working fine. does anyone have any ideas on wat it could be. thanks