Fuel gauge bouncing on 2000 chevy tahoe where is fuel pump relay

I had previously replaced the failing fuel pump on my '98 K2500 when it went out entirely. I was ready to replace my 2000 K3500's fuel gauge as it was acting up.
When I started the engine, the gauge would bounce from the middle to way past full then back. It would also jump sporadically while driving on level ground.
I checked the electrical connections at the tank and made sure the frame ground strap located nearby was making good contact. Nothing changed until I removed the instrument panel and cleaned the connections on the back. The fuel gauge seems to be operating correctly now.
There are videos on YouTube that show how to remove the instrument cluster if in doubt. Mine dash has a pop-in plastic bezel followed by 4 screws to hold the cluster in place. It took about a half hour to inspect & clean the dash connection vs. $250 to replace the pump/sending unit combo. Hope this helps.

Fuel sending unit is in the tank. this is normal after about 75k miles and up. pump and sending unit are sold together. fuel sloshes from front to rear making the float on the sender rise and fall.

Jawz is right, its the instrument cluster. Unfortunately you cannot buy one fuel gauge you have to buy the whole cluster. Its a real bummer because it's not cheap and you have to have the odometer reset to match the correct mileage on your rig. Deal with it, if you can and wait until it no longer works, unless it bugs you that much.