96 ram 1500 no spark

I'm not a dodge man, but I do work with engines that use a crank reference in order to establish ignition. It seems logical that the crank sensor needs to function in order to provide the ignition system with a "reset" signal telling the ignition module when to fire the next sequence. Although after 2 hours of running it doesn't seem like an intermittent issue. Does it run OK before it warms up? If so, then I would check the ignition module. There needs to heat transfer from the module to the distributor body. this is usually done by a film of dielectric grease underneath or white lithium grease. If it's anything like my chevy the ignition module is part of the distributor and can be changed without removing the distributor.