erratic fuel gauge

hello all, newbie to the forum. i have a question re: my 1990 gmc suburban. when the tank is empty, it reads just under 1/4 on the gauge. when the tank full, the needle goes way past the full mark. the fuel sender is ok. is there any way to rig something to the gauge wire with resistors from radio shack or something? i vaguely recall seeing some kind of homemade unit like that for sale on ebay. thanks in advance to all for your help.