Intermittent noise and vibration from driver side wheel on 2007 Sierra 1500
Truck is completely stock. I have owned truck for only 5000 of the 74000 miles on the truck and it drives perfect most of the time. In the past week I started to hear a scraping/ grinding noise on and off of varying intensity accompanied by a rough vibration under drivers feet. I first felt it on a turn but realized it does it on turns and straights randomly. Then I was leaving the parking lot at the grocery store and while driving through the lot I heard a loud popping noise ( loud enough to echo off building and make everyone stare at my brand new looking truck) also accompanied by a jerking feeling below my feet. (Straight or turning) this went on for about a minute then stopped and I drove to mechanic. He drove truck, put on lift and heard saw and felt nothing. I drove the truck home and am hearing the grinding/ scraping noise - sounds like an automatic locking hub going on older vehicles, but I understand that the hubs are always locked on these trucks. This is all in 2 wd. 4x4 seems to be working but I swear I feel some abnormal vibration but not positive. I have used the 4x4 a few times since I purchased including once hauling some firewood out of the woods. This was about a month ago and I thought I felt and heard something then while climbing a hill but brushed it off at the time. Going back to mechanic on Thursday. Any ideas? Front differential? Bearing?