My radiator is leaking.
If your radiator is leaking then it needs to be replaced. Hopefully the engine never got too hot when this loss of coolant occurred. Once the radiator is replaced I would typically do a cooling system pressure test to make sure there are not other leaks. If there are not other leaks, then I would warm the engine up and do a block test just to make sure that there are not any issues with the head gaskets. If that test comes back negative then the truck should be fine from there. If you need a radiator replacement service, a certified mechanic from YourMechanic can come to your office to change it out and perform other tests.