Unless your state will give you a transporter tag, or you can get a temporary permit for a vehicle that you do not have a title for, it is not legal to just drive off, and you are opening yourself up for legal problems.
Plus, you are buying a 100% unknown truck that you cannot test drive and have zero idea of the history on, that has likely been sitting mostly unused for many months and possibly had a number of bad parts swapped on to it before it was sold. If it is a CUCV or smaller, you can likely get away with driving it. Anything bigger and the risks go higher.
My .02- have it towed at least off post to a place where you can give it a good service before trying to drive further. Lots of people drive them off, yes. But they are accepting a risk every time. Are you ready for when the brakes fail, or the front wheel, brake drum and hub come off at 55 on the interstate and roll into oncoming traffic, or when the oil line goes and your engine blows, and the resulting oil spill on the highway causes people behind you to wreck, or when the tires shred and toss rubber all over the motorcycle that was passing you.
I have seen all of the above happen- on trucks that were currently in service. A truck you buy will be even riskier. In a normal drive, you can chalk it up to "stuff happens" and your insurance will cover. But if you just picked up a salvage truck and drove it off post without checking it, without registration or tags, and without even having a title in hand, any abulance chasing lawyer will have a field day with you in court, and your insurance company may decline to cover the damages or may pay out and then sue you.
Are you willing to risk losing all you own in court to save a hauling bill?
My .02. Many here will disagree, and will tell you tales of how many trucks they have driven home. But it only takes one going wrong to ruin your life and cause many headaches for our hobby. Take a moment to seriously consider the risks.
Myself? I will drag a trailer home after I check it out, or I will maybe drive a CUCV after a detailed check (but a CUCV would be more likely to get towbared home). Anything bigger is either being hauled home or taken off post where I can work on it, verify all is well, and do short test drives before I commit to several hundred miles home.
