1994 Ford Thunderbird Need help.

I have a 1991 Ford Thunder bird LX, 4.8 liter v8 with an automatic transmission. The car has 56,000 miles on it. The car was my grandfathers, and has done a lot of sitting. The fuel gauge has been stuck on full for years but, the low fuel light stays on. I have recently replace the fuel sending unit in the tank, nothing changed. The speedometer works but, neither the trip meter nor odometer work. I replaced the speed sensor, and that didn't fix that issue either. I have been trying to find all of the grounds on the vehicle but, this has been a very time consuming process. Also the traction control switch will not switch off. Any suggestions will be greatly appreciated. Thanks