1977 C10 Gas Gauge

[casey3115]

First time posting. I have a 1977 C10 and the gas gauge is on the fritz. A few weeks ago the gauge pegged itself way past full and stayed there for a few days. One day I started the truck and the gauge slowly went back down to around a 1/4 of a tank which seemed about right. All was well for a few weeks until the other day it pegged way past full again. This time it only lasted until I started it again. Then tonight it did it again, went way past full and stuck.
Any ideas? Is this the sending unit or something (fingers crossed) more accessible like a fuse?

Thanks all in advance for the help