Gauges

I need help with this I put a full painless wiring harness in my 1971 Plymouth Duster when I did that I also put in a raylle dash everything works fine except the fuel gauge it either reads full or empty at all times I thought I would change the voltage limiter but the one on the raylle dash isn't the push in kind it's a long sphere looking one with a wire coming from it to the fuel gauge any thoughts