I've heard of a few guys who just swapped computers without any dealer flashing/vin programming, etc, and the truck would run fine.

maybe they were non-security trucks, I don't know.

if your truck does not have the security package on it, then maybe you can get by with a junkyard PCM, just to troubleshoot.

find one out of a truck that was clearly running and driving all the way to the scene of the crash use it to troubleshoot, and if the truck starts right up, then you know it was the PCM. if your junkyard piece fails quickly, then invest money on a more expensive reman'd unit with some sort of a warranty.