I replaced the fuel tank (16 gal) and the sending unit in my 1968 fastback. For some reason it doesn't seem correct. Last week the needle was pointing to 1/4. I stop for gas and I put in just over 6 galleons, so there should be 10 galleons, between half way and 3/4 of a tank. Instead the needle jumps all the way to just under FULL. This might explain why it drops quickly, I drive it for about 15-20 miles and it will drop about 1/8 at a time. It is just an untouched 302 4 barrel with 130000 original miles as so I was told. I am almost certain the fuel guage is off, there is no way I am getting that bad mpg. Was there something I had to do to the sending unit before installation? The sending unit and fuel tank came together as a kit. I just don't want to take the chance one day and run out of fuel because I thought the fuel guage was off. Any suggestions?