Intermittent issue of the truck not starting when the transmission is shifted into park?

Being it is intermittent it could be the cable stretched or a bad bushing in the cable end. To check that you need to go under the truck and look at the cable on the side of the transmission. Have someone hold the brake and move the shifter from park to reverse and see if the lever on the transmission matches those movements, then when they put it back into park use your hand to be sure it shifted fully into park. If it did then it's likely that the switch itself is failing. It isn't that hard to change the switch out. You block the trucks tires, then go to the switch, remove the cable clip and the cable end from the lever, then remove the nut that secures the lever. Next unplug the connector and remove the two bolts and remove the switch. To install the new one, you put it in place and connect the wiring, bolt it to the transmission loosely and then install the lever and cable. With that done you need to adjust it. Some of them come with a tool or include instructions on how to adjust the switch. Without it the common procedure is to put the transmission into park and then slowly adjust the switch until the engine only starts in park or neutral.

Yes, that would be the part.