I own a 2003 Silverado step side. It's been a great truck, love it! I was driving to work a couple of days ago and heard some loud squeaking when I'd hit uneven sections of pavement. I didn't think much of it, but when I got home the next a.m. I started pressing on the bumper and it would sqeak and seemed to be a tad loose. I start looking and there appears to be two holes about 8 inches to the left and right of the bowtie, down inside the grill, that are missing bolts. Sure enough when I push on the bumper the brackets move and squeak. Any way to find out what size bolts? And how the h*** did that happen?

Oh and a truck pic just for fun:

 

Thats interesting! Are you the original owner? If not, is it possible it has had a bumper replaced at some time and the body guy skipped those bolts. You can either go get them from the dealer, take some measurements and hit the local hardware store, or I would go to my local salvage yard - they will probably either give them to you or charge you VERY little for a couple of bolts. Glad you found the problem - squeaks drive me insane!!!!

 

No I'm not the original owner, the truck is in great shape. Whoever had it before me took immaculate care of her. But you may be right about the bumper, it may have been replaced. I'm just gonna run to the hardware store and pick up some bolts and washers... maybe a little lock-tite. Squeaks and little annoying noises drive me crazy too!