Truck was running fine tell radiator went bad and filled up tranny with water.
I have another transmission installed. But now there’s no spark. It’s getting fuel .
it’s a 6 L Chevy 2500 HD.
could it have anything to do with trans install?

 

Good chance of a forgotten connector that's just dangling. Another probability is that a wire(s) was pinched and severed in the removal/installation process that caused this problem. Outside of a coincidence, not much else makes sense.

 

I looked up where the crank sensor was because I was going to test it. Lo and behold it’s behind the starter, dangling there was a plug.
yes it was the plug for crank sensor.Plugged it in truck fired right up.

 

Thank you for the update.