Gas Tank Replacement

Much thanks to everyone for their help regarding the gas tank of my ’63 Falcon. While I liked the idea of going with a new mustang tank and an internal (and secure) filling option. Jerry was kind enough to offer up a tank from his ’65.
I popped out the old tank out (image 1) and then prepped the trunk area around the tank (images 2 and 3). I then lined the opening with double sided tape to form a good seal before dropping the “new” tank in (image 4). Jerry the tank looks great! Thanks again for your help!
I wish it went as easy as 1, 2, 3, 4…but the old tank was not bolted in, and when they put installed the new exhaust, they encroached on some of the tank space. So I need to try and realign the exhaust system. Also when I went to hook-up the gauge (something I was very excited about doing) I could not get the hook-up to slip on. Does anyone know a trick for this?

Your sending unit, if it's like mine, has a short piece of wire with an eye on one end and a main bullet connector on the other. The wire is only about six inches long. The eye attaches to the tank with a small washer and nut and your gauge wire connects to the other end.

Thanks for the reply-
Here is where I am at (see image).
I don't know how much pressure to apply to get the sleeve (of the gauge wire) to slide over the threads protruding from the sending unit.
I thought the sleeve would just "slip" over, but that was not the case. So I thought I would ask, before I screw up the sending unit, etc.

Although knowing how much is in the tank would be great...a more pressing issue, is what is a minimum safe space between the muffler and gas tank. As you can see from the second image, they are currently touching at the rear of the tank. I need to move everything over at least a 1/2 inch to get the tank holes to line up...so I want to make sure to get the muffler moved far enough away on the first try (like that is going to happen!).

Pbrown, I was wondering if you could put some pics of the sending unit because I can't really see what you are talking about. My sending unit is in but it is just not registering on the gauge. Can you help with advice?

Sorry but I don't have a photo. You can pull the sending unit to test. Connect the gauge lead to the sending unit stud. Then attach a ground lead from the sending unit to a good ground. Turn on your ignition and move the float up and down. Have someone watch the gauge and watch for movement. Note that the gauge moved slowly by design so it will take several seconds to see your float movement register on the gauge.

Check your float for leaks. A float can sink and cause the gauge to read empty.

Thanks, I will try it.

Success at last…
With a little more effort I was able to attach the gauge lead to the sending unit stud. The ’63 and ’65 sending units are not identical, and thus it was hard to get a straight shot at things with the gas line all connected. But once I disconnected the gas line, things went together in a snap.
Jerry, the best news is that everything works…and now I have an idea of how much gas is in the tank. I’ll fill her up soon and go from there.
I am a big believer in recycling, so I am glad I could put your tank to good use. Now to pay it forward I have some items I can make available to anyone who needs them:
Fuel Sender Ring Gasket
Locking Ring
I can even pass along the Sending Unit, although it needs a float.
(Sorry for the dark images...I have enhanced the fuel markings in the image.)