Bill:
Ford make a float that
fits. If the website is back up check the archives for "Ford Float" and
I believe you will find it. If not e-mail me off the list and I will
find it for you. With that said I don't believe your problem is the
float.
Start by taking the wire loose at the
tank. With the wire disconnected the gauge should read "E". Ground
the wire momentarily and the gauge should go up to or past "F". If you
can have someone in the car to watch it so that you don't have to leave the
wire grounded for very long as gauge damage can result. If the gauge
does not respond or doesn't respond correctly then your problem is either in
the gauge or the wiring. If it does respond then you have a sending unit
problem.
Where the gas line connects to the tank there
is a small section of rubber hose between the line on the body and the sending
unit. There needs to be a metal clip bridging this piece of rubber
hose. If it is not there and making good connection you will have a
poor/erratic ground on your sending unit. The way yours is acting I
suspect that this clip could be the problem.
Steve B.