Cut that weld, its not factory. Then your fender should come off. The white part should stay with your fender unless the spot welds are rusted out and it falls off. Alot of the time the seam spreads apart because they will rust between the pieces. A new fender will come with that part connect to it. Just dont cut your grill support while cutting that weld or you will have more work to do.

How do I know so much about these trucks?
I stayed at a Holiday Inn Express last night.