I recently installed a new gas tank in my 1955 TBird. The tank went in without a hassle.  I ordered a new fuel gauge sending unit from Macs and they sent me a universal sender from Dennis Carpenter.  I followed the instructions and can't get the fuel gauge to read correctly.  The arm with the float on it hangs up.  I took it out and the pressure required to move the float up and down is substantial.  I am under the impression that the float arm should fall with gravity alone?  My car is a 55 that has been converted to 12 volts. This unit is suppose to work with either 6 or 12 volt systems.  Anyone else have this problem?