not true per say, you can drive any year vehicle you want, BUT as with any vehicle, old or not, to operate it on public roads, you will be required to keep the old truck in proper condition, this means replacing / repairing any worn parts like in the steering and suspension, the brakes must be in excelent condition, and stop the truck straight and quickly, [ some of these parts may be scarce for older medium duty trucks] the engine, trans,rear end, ect, no external oil leaks, no excess blue smoke out the exhaust, some people like myself, finding newer trucks to be too expensive and full of computer glitches chose to run older vehicles, besides in todays cookie cutter trucks, the older ones look cool too, lol, sometimes it is to the owners advantage to install a later model drive train in a older chassis, this gets around the parts availability problems, gives the truck greater power, and more road speed, remember most medium duty trucks from the late 50's and back are geared to top out around 50 mph, with the roads of that era and the engine power of the day that was plenty fast enough, also if the truck is sporting a set of those r-5 wheels that split in the middle of the rim, those got to go, they were not a good idea when new, and many serious injuries and deaths were caused by them blowing up when a tire was installed and the rim was not properly seated, today, there just plain dangerous, and tire shops will not work on them, a late model rear end gives a higher road speed, and allows you to run modern tubless wheels too, if you get to this point the older trucks are plenty good, and insurance runs about the same as any other farm truck of the same class