intermittant fuel gauge problem

[Piersol]

I bought a '05 2500 diesel with 9500 miles last spring. Nice improvement over my '96. A week after I bought it I filled it up and the next day the gauge read just over 1/2 tank. I thought someone was stealing fuel so i filled up. It took about 2 gallons. Problem never happened again untill this week. Gauge read full after fillup but the next day (took the truck to lunch and the gauge read 1/2 tank). Started it up to go home and the gauge read full. Any thoughts?

 

[EErmert]

Hey, did the fuel tank have the "mod" for the vent installed? This could have a diffenet bearing on the fuel reading gage...