Fuel Gauge Issues

[1972BlueC20]

My fuel gauge and sender are both new.

Gauge is real bouncy while driving when half full or less, and when I fill the truck up it goes way past Full.

Any suggestions to remedy this?

See picture below. Tank is still a few gallons shy of totally full.

[FirstOwner69]

My truck had idiot lights. I bought a tach cluster on eBay and cobbled together a cluster using my original speedometer/odometer and gauges from the tach cluster and various other clusters I'd accumulated over the years. The fuel gauge bounced wildly from fuel sloshing, especially from 3/4 tank down. I hadn't driven the truck for years, but did not recall the bouncing fuel gauge. I read here that one possible cause was that the needle may not have enough built in resistance to rotation. I removed the gauge and blew on the needle. It spun around freely. I did the same with my original and it barely moved. I put the original in and problem solved. Do you still have your original?

It's common for the gauge to go past full and stay there quite a while. They are not linear and the sender float in it's highest position is not quite at the top of the tank. It is somewhat submerged. Have you driven the truck enough since your gauge swap to see how it reacts as you approach empty?