Pshaw!! If a graduated stick was good enough for Henry, why, it oughtta be good enough for you.

lol nothing says fun times like running out of gas in the middle of no where cause you forgot to check your fuel stick.

1956 Ford Fairlane Town Sedan - 292 Y8 - Ford-O-Matic - 155,000 mi

My car was converted to 12 volts before I bought it, so I'm not sure that gauge I have.  It's most likely the 6 volt unit.  The former owner was running 12 volts with a positive ground.  I switched the battery cables and all has worked for a year so far. The gas tank repro sender is erratic.  It sticks on full.  After a while it shows correctly.  For now, I'll keep the tank full. The car runs so much better with a new gas tank.  Rust dust was getting by the filter and into the carb.

To run 6 Volt Gauges- Fuel + Temp there should be a small voltage Device on backside of Dash. Steps down voltage from 12 to 6. The only Year that Ford used 12 Volts on Gauges was 1956. All other 12 Volt Systems use reduced 6 Volts for Gauges..

  

I filled my TBird this morning and the gas gauge went beyond full.   I believe the new sender has a different oms range than the original. I noticed my original sender had a resistor in line with the ground.   I am going to check the range of my old sender and compare it with the replacement.  I may need to install a resistor to make it work right.

The biggest Problem with these replacement Senders is the Ohm Range is wrong. The Ford Senders are 73-10 Ohm Range. Using a Multi Meter set to Ohms connect the Red Lead to center Post of Sender and Black lead to the outer body where it screws to Tank ( ground). Moving the Float Arm from lowest Point to highest Point should read between 75-10 Ohms. Full to empty. You can do this out of the Car. Bench Test. If the Ohm reading is not close to Specs it won't work no matter what You do. The "Resistor" you mentioned is actually likely a Condensor. I  forget why they were installed but I have heard of these before but not shown on Illustration in Parts Book. Kultulz will probably know about these Condensors. If You do a Google Search relating to Ford Sending Units there's lots of Information out there. Too bad U can't repair Your Original or find even a good used Original. On my 56 the Gas Gauge was erratic. I opened up the little Cover in Trunk which should have given Me access to Sender. Wasn't there! Someone put a 55 Tank in which Places Sender further forward under the Trunk Floor.If I want to access it I have to drop Tank. if I was at that Point I would replace the Tank with correct One.. I asssume the Sender in mine is a 56 but because its not positioned where it should be on the Tank it doesn't read correctly. There's a lot of complaints on the Internet regarding these Aftermarket Senders not working as Advertised. By the way the 55 T-Bird Sender is the same as the 55 Ford Passenger Car Sender. Might help U find a new proper Replacement or a good used One. Maybe Carl has a good used One.

  

Bob's Speedometer Service says they can repair King Seely senders and guages.

https://www.bobsspeedometer.com/1/120/services.asp

I just checked Hill's Thunderbird Shop. They do top Quality Restorations and sell Parts also. They have a new replacement Sender for 55 $57.95. 56 $57.95. They also have a replacement Set with Dash Gauge and Sender $149,95.They have those in 6 or 12 Volt. The 55 or 56 Sender should also work in 55 and 56 Passenger Cars. I would trust these Guys a lot more than any of the other Aftermarket Parts Sellers. They use in the Shop what they sell Online.

  

I had trouble with my 56 Victoria. After playing with it a while I came up with mounting the sender on a 2 x 4 in the trunk sitting on it edge. I turned on my accessory key and started watching the gauge as I moved the float arm in an arc. Be patient as it reacts very slowly. Before I started I measured the tank depth and set the float low enough where It would be sitting on the bottom which to me would mean buy some gas. It was about 1/2 tank as I remember.
I found to get the gauge to read empty in needed to shorten the arm so I started bending in "Z's"  until it did, I then slowly moved it up to where I thought the float would be floating on about 1/2 tank than also where to float would be pushed up against the top of the tank hoping for a full reading. After a lot of bending the arm and multiple tests I got it "close enough"
I doesn't move off full for 50-75 miles or so, 1/2 is 1/2 and takes about 8 gallons. Right between 1/4 and empty it takes 13 gallons so that's where I left it. I had the sender out at least 4 times.. Mine gets about 10 mph with all in town driving and I'm OK with it. I have gone 150 miles but normally not. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Regarding BOB' SPEEDO, read this page- https://www.bobsspeedometer.com/1/120/news.asp?artID=43858

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