will any other ford sender unit fit my 90 spec efi xr3i, mine has 2 plugs on top and on the inner side (inside the tank) of the sender unit there is a little black box where the power and earth go into, i have got power going to this but nothing coming out of the other side towards the pump, is there any way around this because i just cant find one anywaher and my car is dead . PLEASE HELP