When I go to turn my truck on, it will not start, its in park but if I put it in Neutral, it will start?

I am having a similar problem on my 1997 chevy 1500 extended cab. I thought it was the starter at first, one day when it wasn't starting, I held the key, put my foot on the break, pulled it out of park, and when I put it back into park it started. I assume it is the sensor/switch that makes sure the truck is in park or neutral before starting. I'm trying to figure out how hard it is to replace the switch.

its called the neutral safety switch its located inside of the steering column all you have to do is remove the plastics from your column unscrew it from the column (take battery out before staring repair) i like to mark what wires go where with paint markers or labeled tape at that point the simply screw the new one into place reconnect wires put battery back into vehicle and make sure it starts in neutral from that point if not you would have switch wires somehow so pay close attention...if need video help look on youtube and there is step by step videos of how to correctly replace it with ease