So I'm currently looking into buying a used Cummins 12v and to make sure I'm not getting ripped off what are some quick things to look for besides the obvious cracks and leaks?

 

ball joints, tranny, u joints, brakes, rust, turbo prop play, blow by.... just to name a few, noticed that the truck might need all that, still doesn't mean you are gonna get it for free, the value of thing are only determine by the willingness of the people doing the deal, it all depends on how much is the prospective buyer willing to pay and how much is the seller willing to lose.