Fuel gauge problem

[FlameOut]

I know this item has been addressed a million times, And I've read many of the threads, but is there a way to test the actual gauge with the instrument cluster out of the truck?

I pulled my seat and then removed the sending unit, thinking that was my problem, but I'm getting the 0-90 ohms when I test it, and when I manually operate the float when connected and grounded, I cant get past about 1/3 of a tank on the gauge.

I removed the instrument cluster, cleaned every connection, but still won't go past 1/3. I'm thinking the actual gauge might be bad, but not sure how to test it. I have the basic inst cluster with idiot lights, but also have a spare cluster with all gauges. Is there a way to test using the 2nd cluster that I have? Can the fuel gauge be removed from one and put into the other?

Everything appears to be properly grounded properly