There's nothing wrong with a DC generator system that's properly adjusted and maintained. They worked for a lot of years before we had alternators in general use. One advantage, if you've got a standard transmssion, is the generator can develop enough output on a push start to get you going even with a totally dead battery. The alternator system can't do that. It has to have at least a little battery voltage left to excite the field coils. Unless you're planning to support more electrical accessiries than the truck had originally, a good-working generator shouild be all you need.
Jerry
