70 R/R needs replacement fuel tank advise. Please.

Hello All. I am REALLY new to my recent purchase of a numbers matching, 383 Roadrunner. After my purchase last year, I have found that I am only able to add about 4 gallons of fuel to the gas tank BEFORE it starts to leach-out of one of the what I believe are vent tubes. I will attempt to attach a couple of photos to this post to try to show what I am speaking about. Anyways, I looked at past posts, and see that most of you recommend "Spectra Brand" replacement tanks... Looking at what they have to offer, I am once again confused as to what tank I need.... Again, hopefully, I can attach these photos, and someone can help! Also, in one post, it was mentioned that a "premium tank" should be purchased.... Do they make several quality styles? If so, what should I invest in for a car that I hope to keep for a long time? ( maybe even stainless?)
Currently, the fuel guage IS working inside the car... Should I invest in a new tank sending unit too since I am replacing the tank? Also, it looks as if the seal on the sending unit must be installed PERFECTLY or it too, may leak... Do gaskets come with the tank and or sending units? And if so, are they decent gaskets? or should I purchase a "better" one from somewhere else? Any tricks of the trade for getting a perfect seal I should be made aware of?
Hey, sorry for all the dumb questions, but I am simply trying to get all my ducks in a row, and not starting a replacement only to find myself scratching my head half way into the swap, and wasting cash that as you all know is not easy to aquire.

I appreciate any and all feedback to my silly questions. Thanks, in advance!

Now, let's see if I can attach some photos of my old, leaky tank......

The spot that is leaking is the stem, or nipple on the far right side of photo where the new gas line can be seen, where the stem attaches, or should I say enters the tank (bad weld/seam?)....

the gasket will come with the sending unit,as for the tank there are alot of good new gas tank dealers out there

Hi skrambler,

Not dumb questions at all. Congratulations on your Road Runner! I also have a 70 Road Runner.

First things first: There are TWO fuel tanks for 70 Road Runners, depending on where they were made. Those made for California have a Clean Air System (CAS), and they have a different tank. So first, let's determine if you have a California car: There are two easy ways. First, look in the trunk on the far right (passenger) side. See if there is an angled tube there coming up from the trunk. If there is, you have the Clean Air System. The other way to check is to see if it was made in California (I believe that all CA cars are CAS, and all non CA cars are not - but don't hold me 100% to this). California cars are identified by the VIN: RM21N0E. If the seventh digit is an "E", then it was assembled in Los Angeles.

The above information will be important if you need to order a new tank.

Your tank doesn't look horrible. Are you sure the tank itself is leaking? You may just have a bad steel fuel line or connection. Also, if you have a CAS tank, there are four lines coming from the tank to the vapor recovery tube in the trunk. Check those too.

I have not had to replace my tank, so I can't offer any advice on the best new one to purchase.

Good luck!

If your gage works and is accurate keep it,I replaced mine with an aftermarket one and it is off by half a tank.

I have the spectra tank and is form fit function of the original. I would say your leak might be coming from the hose to nipple connection and not the tank itself. Either way as long as there is no fuel in the tank its a fairly easy job. As for the senders my new repro works great, I got it from Jeff at 521restorations he's a member on here. The ring gasket for the sender is very finicky and your sender has to be perfectly centered to get it to seal. I guess they make a tool for this but I was able to get it from under the car with a BRASS punch and hammer after a few trial and errors.

I would say reuse your metal ring though, the repro ones seem to not be as thick. If you do reuse your old sender you'll probably need a new sock for it.