2001 chevy Silverado LS gas gauge reads empty in Park and jumps to actual level when I shift from park to Drive

Hello, my initial thoughts is that there is a concern with a common ground to the shift lever mechanism and the fuel sending unit. There's so much more to know about a 23 year old vehicle that can't be guessed at in this forum. So, some hands on testing is needed to figure out what's going on. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops