So basically if the oil is discolored/milky the motor is 100% going to be bad is what I'm hearing.
Not necessarily. They may have been driving, saw the temp gauge rise, shut it down to check everything, saw the milkshake and left it off and towed it home. Unless you or they can prove that it wasn't ran much on the watery oil, the truck should be sold assuming the motor needs rebuilding or replacement. If I were selling it, or even just for my own testing, I'd drain the coolant and change the oil so it could be started and ran for a few seconds for prospective buyers. If it sounds fine and has good oil pressure (allow for 10-20 psi drop once warm at idle), I'd probably roll with it but still leave room in the bargaining for a replacement engine, even if it's a $500 junkyard pull. Of course, this all hinges on the rest of the truck being worth it to you.
...but I may be looking at a 1996 dodge 2500 with a 5.9 magnum and a blown head gasket. Dude wants to trade for my 20x14's. So the net cost for me is $850, and the truck is fairly clean. As far as I know it hasn't been extensively driven on the bad head gasket. And if worst comes to worst it comes with an extra engine but the history on it is unknown. I know this doesn't exactly relate to anything here but other forums haven't been any help at all lol and the info online has been spotty at best.
Unless you need a 2500 truck, I'd pick the GM over the Dodge, and that's not an opinion biased by being a GM or Ford or Dodge lover/hater. I believe each has their pros and cons and those vary with generations. Generally speaking, that generation of Dodge had a fairly solid drivetrain but everything else was shit. If I had to pick an engine to replace a head gasket on, I'd go with a Gen3 GM long before a Gen2 Dodge. If I had to pick it for the truck itself, regardless of the drivetrain, I'd still pick the GM.
