Installing a Mustang tank in a 60’s vintage Ford

Installing a Mustang tank in a 60’s vintage Ford F-series pickup

Greeting fellow Ford truckers. One of the few things not to like about the early model F-series trucks is that you are sitting on about 18 gallons of gasoline. Personally, I didn't consider this to be one of Ford's better ideas, so I began to look around for another way. On the Ford Enthusiast's internet site there was an article on how to put a Mustang fuel tank in a '53-56 Effie, so, after carefully reading that how-to, I reasoned that it should work in the 57-66 models too.

I picked out the Mustang unit for several reasons. One, the fuel sender is compatible with the stock instrument gauge. Two, they come in three sizes; 16, 20, and 22 gallon units which are available new. And finally, since there isn't a lot of extra room under the trucks and I didn't want to have to notch the frame to put in a side fill unit, it seemed to be the logical choice. Besides, I like gadgets and the boat style deck fill that is mounted in the bed looks trick. And, as it turned out, the installation was pretty straightforward. So, follow on, look at the pictures and see how I did it. As for measurements, all I have is for the 61-66 trucks so you 57-60 guys are on your own.

The Mustang fuel tank has the same over all dimensions from 1964 through 1971 with the exception of the height of the top of the tank measured from the mounting flange. The 1970 22 gallon unit I used is about 1-1/2" taller than the 16 gallon unit but I opted for the extra fuel load. You can't put a spare under it anyway so go for the bigger capacity. This is what the original Mustang fuel tank looks like. Note the slant of the filler neck. This will be changed later on. The filler neck goes to the rear of the truck. The length of the tank is 21" and the height of the tank from the mounting flange is 2-1/2".

The first step, of course is to measure everything. The frame measures 34" to the outside and 29-1/2" to the inside edge of the frame. Since the tank is 30" wide, we already have a problem. Second, the last cross member will be in the way of the tank unless you drop it down to clear. I drilled the rivets out and moved the cross member to the back of the frame where it will be bolted and welded back in place. I turned it upside down for clearance and backward so I could access the bolt that I used to attach the fuel tank frame in case I ever wanted to take it out. You'll see later.

When you get the cross member out, trim the bottom inside of the frame about 3/8" on both sides.

Here is how it looks with the trim lines.

The trim lines were marked on some masking tape and I cut mine with a Saws-all and then finished it up with a grinder. Here is another shot that shows the rear cross member flipped over. I don't know if you can see the trimmed area or not, but it is trimmed.

Look close and you can see the deck fill inside the frame. Here's a better look after everything is cleaned, welded up and painted. Note the kick up. It goes to the front. The other one is flat.

Here is the rear tab bolted to the rear most cross member. The tank now sits level. I used self tapping screws through the fuel tank flange to fasten the tank to the frame. Only used one on this tab, two on the front one.

Remember what I said at the beginning about the filler neck? The original comes out at an angle so it needs to be cut and re-welded in a vertical position. I used some 2" muffler tubing and had it stretched at a muffler shop to fit inside the original hole. It takes some trial and error but it isn't to hard. Don't forget to drill a hole and weld in a vent tube while you're at it. The boat style deck fill fits water tight and if the tank doesn't vent, you got problems. The following shots show you what it looks like.

Make sure to find a way to keep the shavings out of the tank. I used a magnet and some paper towels. I also used my shop vac after I got everything cleaned up. Everyone has his or her own way to do this, I just cut the damn thing off flush.

Not to bad. See how the tank flange sits on top of the frame and the screws that hold it in place. I think I used about 6 screws just to keep things in line. Notice the vent line. I will run tubing from the vent to the side of the truck from here. The vent is important.

Well, now that we have everything cut, fit and screw down, its time to put the tank in the frame. Here is how it looks.

Finally, its in the frame. The last photo shows how much room you will have above the tank to the frame. When I put the bed on, I will have to cut a hole in the floor for the deck fill. There will still be about 3-1/2" from the bottom of the filler neck and the deck fill and that will be connected with fuel filler hose. I left as much room as possible so I could get up under the bed to tighten the hose clamps.

"Topping off/ finishing the Mustang Tank Installation"

Since you've already read the article on installing a Mustang fuel tank in a 1961-1966 F-series Ford truck, aka "Slick 60", and are contemplating doing the same thing to your own truck, I'll bet you're wondering how I plan to finish it out.

A good friend once told me the art of bodywork is simply making big scratches into small ones.

He lied of course, it’s a lot harder than that.

But the "Zen" of it worked out very nicely for me when I began to finish my Mustang Fuel Tank Installation that you've already read about.

I hate to say it, but I originally had a flare side bed planned for my truck. Installing the stainless filler in some nicely finished wood was going to be a no brainer, even for me.

But, when this really good, 40-year-old style side bed came up for way cheap money, I had to change my plans.

And, because I was committed to using a $ 50.00 stainless filler cap I had already bought, I had to come up with something that wouldn't look like Gomer Pyle did the work with a hack saw and a rasp.

So I went to the garage with an adult beverage, sat quietly, and had my moment of Zen that I always talk about.

As a result, I humbly submit to you the ideas that follow.

It turned out pretty well if I do say so myself, and I'm sure if I could weld like some of you, it would have been a masterpiece. Despite the fact that my welding skills produced what my buddy Tom called "goobers" all over the place, it finished out and looks pretty good. Feel free to expand and improve the idea as you see fit, but remember, nobody likes a bragger.

You already have the Mustang tank in place, so let's start there. Using the bed mounting bolt holes in the bare frame as a reference point, measure and triangulate the location of the center of the filler neck on the fuel tank using those points. I put masking tape on the frame so I could record the measurements and mark the intersecting points.

Repeat the process on both sides to make sure you have the foci (center) located properly.

I also made notes on the tank with grease pencil. If you look close you can see them in yellow.

By the way, triangulating is an uptown word for geometry. You get to draw some straight lines and make them run into each other at a pre-determined point.

Measure several times. No problems, but remember the old woodcutter's rule, measure 33 times, cut once. We have to locate the same point in the floor of the bed, so that’s why we're triangulating the mounting holes. Keep notes for later.

These measurements and lines locate the centerline for the tank opening using the truck frame as reference. I used the mounting holes in the bed and the frame as a reference point, because they exactly match the mounting holes in the bed floor. The centerline of the tank opening is related to those mounting holes. Just transfer all your location points of reference from the frame and tank and mark them in the bed floor. Sounds complicated, but trust me, it isn't. Just follow the pictures

You can use any method you want for mounting the filler cap but here is an idea. I have a friend who is a retired sheet metal professional and he bent me a 4"x7" tray and cut the hole in the center for the filler neck to fit in. The lips are about 3/8" high. They are to big and the tray is too long, but it gives me room to trim and fit later when things are tacked in place.

I think you're beginning to see where I'm going with this one.

I put the pictures in to show you how the filler will fit down on the tank.

But I think you can see that the whole process is pretty simple if you take your time and think things out. You don't have to be Boyd Coddington to make minor custom improvements to your truck; you just need a little pre-planning and spend some time thinking out your project and make the effort to make things right.

Just remember your moments of Zen. (Oh yeah, if you weld like me, practicing your welding before you start the project helps too. Trust me on that one.)

I guess you can now see how easy it is to get the fuel out of the cab and outside where it belongs. Also, by looking at the pictures, I think you get the idea as to why I didn't try to put the filler out the side. Maybe someone else will figure out a better way, but for me, this was the simplest solution to a bad problem.

This concludes my little project and I sure hope this little article gives you some ideas on how to move your own fuel tank. If you come up with some more good ideas, please let me know.