Door striker issues
 

Let me start out by saying, I've pulled alot of information from these forums without ever registering in the past few years. Thank you all for the huge amount of wisdom contained here.

Now, the issue I am needing help with is this. I have a 67 (mostly - its a conglomeration of 67, 69 and 72), F250. The door striker has what appears to be a washer centering it, which has broken off, I'm assuming mostly due to either metal stress or rust. This means the door doesn't shut well at all, as the striker wanders up to an inch or so inside the door frame. Fixing it would be easy but I can't seem to find anything that explains how it is actually assembled, and it most definatly doesn't seem to want to unscrew from the back as I would expect.
Before I resort to force (and vice grips), I wanted to ask to see if there was any suggestions.

Thankee.