My bodyshop friend said you can adjust the door without removing the fender. Losen up the striker just enough so it has some play. You don't want it moving on it's own, just enough to push it up or down. Losen then hinge bolts on the door, then align it to where you want it. Use a shim to fill in the gap needed to align the door correctly, then tighten the hinge down. Now adjust the striker to work correctly with the door. If that doesn't work, then you'll need to go after the hinge mounts behind the fender like Chuck mentioned. I didn't get a chance to check my own truck (keep forgetting), but it should be pretty standard. Hope that helps.