Lifted from the BC Broncos Site
--------------Begin snip----------------------------------
FUEL TANK SENDING UNIT
The sending unit comes with our tank. This is a replacement unit with the 5 screw holes (round plate). This is a standard in the aftermarket. We used this on our early style fuel tanks (for about 5 years) until we made the change to the in-tank fuel pump design in 2006. Now we use a 16 hole (square plate) design. The plate is different but the sender is the same. This sender will work with a stock Early Bronco fuel gauge or any aftermarket fuel gauge that requires a ohm range from 10 to 70, meaning that if you test your fuel gauge, you should get around 10 ohms when the tank is full and around 70 ohms when it is empty.
-------------------------End Snip-----------------------------
There ya go!