Door striker issue

[jdl71]

I'll be the first to admit I'm pretty ignorant when it comes to door adjusting. I've looked at the factory assy manual and read some previous threads on here but I'm still at a loss. I have to really, really slam this door to get it shut. From the looks of things it appears to me it's too high in back:



When it is shut though, it doesn't appear to be that misaligned:



I suppose that could be due to the striker forcing it down. I've taken all the striker bolts loose and tried to move it up/down but it only seems to want to go in/out. If I leave the bolts loose the door will close properly, but as soon as I open it to tighten them I'm back where I started. The cab support and floor is not overly rusty on this side so I don't really think it's sagging in the front. If I need to use the hinges to adjust this, which one's should I loosen and move around?