Hi, Does anybody here know of a good body shop in the San Francisco, California Area?

Or does anybody have any advice how to stop or treat rusted, pitted body/exterior?

You probably won't easily find a body shop that will repair rust. At least not cheaply. Most places, other those that specialize in restorations, won't even bother with it because there's no money in it, or they'll price it so high as to not make it affordable. I'm in Texas so I can't give you any ideas of where to start other than to ask around and get some prices.

As for fixing the rust, the absolute best way to fix it is to cut it all out and weld in new pieces. If it has holes through the metal, then it's too late. You have to cut... If there are no holes, then you may be able to treat it. But if it has pitted, you're probably out of luck again because Nissan was real bad about using thin sheet metal. With the pitting, you're already too thin.

Of course, you could always use this as an excuse to learn how to do metal repair work and learn how to weld...

Sorry about the negative tone with this, but in order to do it right that's what has to be done.