Fueling & Injection - Nasty Nate fuel gauge problem. Anyone else had this happen?

I got a tank with a 0-90 ohm reader, and switched it to a 40-240 unit from nasty and installed it, and it works fine just is reading wrong when in the tank. When the car is pumped full it reads about 5/8 full, and empty is around 1/2 tank. Anyone else had this problem???

I already tested the gauge, its fine. Tested the sender tilted it upside down when out of tank and all worked fine. Same as when upright it reads empty on the gauge.

Are the wires reversed at the plug?
Is the fuel level for the 4th gen bucket?
Do you want to sell the 0 to 90 ohm fuel level sender?
Can you post a photo of the sender.

Are the wires reversed at the plug?
Is the fuel level for the 4th gen bucket?
Do you want to sell the 0 to 90 ohm fuel level sender?
Can you post a photo of the sender.

Wires are right, yes its for the 4th gen LS1, yes, and yes. I will tonight.