I had the fuel tank on my '88 S-10 replaced late last month. At 18 years of age, the bottom was starting to rot out. With the new tank, I was told that I needed to replace the sending unit as well. I have only gassed up a few times with the new tank, but I have noticed that my gas gauge is not as accurate anymore. With my old sending unit, when the gauge was at 1/2 tank, I could be reasonably sure that I had about 10 gallons remaining, and at 1/4 tank, 5 left in the tank. However, with my new sending unit, 1/4 tank means about 8 gallons remaining (that is, I can put in 12), and at dead empty, I can put nearly 16 in. I do trust my mechanic, but at first I wondered if he goofed and gave me a 16 gallon tank by mistake (I think that is the tank size on 4 cyl S-10s). I did verify that the part number of the tank that I was given is for a 20 gallon tank, which means that there is a problem with either the sending unit or the gas gauge. Is there anything that can be done to fix this problem? I would like to avoid dropping the tank unless absolutely necessary.