since they look one piece i was wondering if the side is metal or if the whole skin is fiberglass?

Actually they are a plastic. Cant remember the name for it, but i do remember repairing alot of them when i worked in a body shop.

They are a type of ABS plastic and a real pain in the ass to fix correctly.

The 08 and up are steel! Gm should have made them steel since th beginning!

ohhhh okay.. is it common to get spider cracks or breaks with these like fiberglass? im looking in to buying this year truck and just lookin for advice. thanks guys.

They get cracks in them just like any of the other fenders. But when something makes good contact with them they shatter into pieces. I have had several of these trucks and only lost a fender when I was hit by an old lady backing out of Kroger parking lot.