Light rod knock in a Durango 5.9... is it terminal?

If you end up trying to change the rod bearings, this is how I did mine in my Dakota. Jack up the front of the truck, Slide the bolt out of the motor mounts, put the transmission in neutral, take out the spark plugs, drain the oil, remove the fan shroud, put an engine lift in place and pick up the engine until the transmission hits the firewall. Then you will have enough room to pull the pan. With the spark plugs pulled you can turn the engine over by holding the balancer and turning by hand. If you get them changed to before it burns through the zinc, the journals will still be fine.