Truck will not start unless we jump it?

Unfortunately we need to stick with the battery and find out how you tested it as we need to load test the battery first to make sure it can handle the load of turning the starter. You may have 12 volts on the battery but it can't handle the amperage draw needed to turn the starter.

Here is a load test that we need make sure this is the test we need to do:

https://www.2carpros.com/articles/car-battery-load-test

Once we know that the battery passes a load test then we need to inspect the wiring to the starter as if you have high resistance then that will cause you to lose voltage and it will cause you to have to add more voltage to it in the form of a jump start to get it to start.

https://www.2carpros.com/articles/how-to-check-wiring

Basically we need to go to the starter and check the voltage and make sure you are getting 12 volts on both wires at the starter.

Please see the diagram below and let us know what you find. However, if you don't find battery voltage there then we have wiring issues.

Thanks