I filled up my truck sunday and put 29 gal. in it. My fuel gauge would not go past 3/8 of a tank. I have a 90 350TBI and the tank that was with it. I was told if it did that it was the sending unit. Well today when I was driving home it started to bounce all over. Know it is pas the full mark, its as far right as it can go and does not move when I turn my k5 off or turn it on. Could this be the sending unit or the fuel gauge that is f**ked up? Yes the instament cluster is out of the 90 along with all of its wiring. Also the gauge worked fine before last sunday.