While driving on Interstate 20 at a 75 mph speed in traffic, the truck began a loud knocking noise and the engine shut down. After fighting the dead truck off the roadway from the highway speeds and avoiding traffic, I was able to get the truck safely stopped. Upon attempting to restart the engine, the starter caught on fire. I was able to get the fire extinguished with minimal damage. The truck was towed by a wrecker to my home. I replaced the starter and inspected the wiring harness for fire damages. The truck did restart after sitting for several days, and the knock which was heard on the roadway the day of the failure was excessive. After other checks and inspections, the crankshaft was found to be broken in half causing loud knocking. This is a catastrophic failure with a monetary replacement of approximately $20,000-$30,000.