Diesel Bombers - future diesel owner

Hi guys, let me first tell you that after a few times of looking at your page I got hooked on trying to buy a diesel. My budget is limited so please be patient as I am new to diesel technology to, basically I have a $2500 to $3500 budget, I looked around and there are a couple trucks I am interested in, a 85 f250 non turbo and a couple cummins inter cooled and non inter-cooled. Obviously you get what you paid for, and with a limited amount of money the trucks are not a show truck or tricked out or anything like that, what should I looked for on this trucks, I know cummins are more desirable for the turbo and bullet prove reputation, while ford as far as I know get more mpg (maybe?) and may be cheaper to fix. This trucks are california trucks so there is no rust and they are not farm trucks either so they are clean (faded paint, worn interior and stuff like that) any info would be appreciated, I will also continue to check the post and threads on this site for more info thanks for your time.

Sorry I could not upload pictures.