[Mister Pontiac]

I had another thread about this topic, but my questions were answered there, so I decided I would post the details of the install here as it pertains specifically to the updates/upgrades for the GT.

Today I finished the install of the 70 Grand Prix fuel tank into my 72 GT, and thought I'd share some details about the swap. I'm very pleased with the outcome, and I've attached a couple pictures of the what it took, and what it looks like after the fact.

The car now carries almost 25 gallons vs. the original 20 gallons. This was important to me as it not only will help feed the thirstier 455 going in the car (soon!), but it will also help with fewer fuel stops, especially on long highway runs. The GT is seeing more driving and longer distances lately (and for the foreseeable future), so this was the reason for making the change.

2. The install went exactly as planned. I had to create two new mounting points for the longer tank straps, so I simply modeled what the factory Grand Prix mounts looked like. I wanted to keep the straps attached to the body at both ends (though it took a bit more work) instead of simply slotting and attaching them to the frame crossbar out back. I thought this was best due to possibility of flexing from the bushings between the body and frame. It's a nice, solid mounting, just as the original tank was. Body to Body, at both ends of the straps.

3. So after filling the tank earlier today, and taking the car for a good drive (city and highway), I noticed that when full, you can not only feel the weight of the extra 5 gallons (maybe 35-40 lbs), but since the weight is added to the aft most part of the car, it acts as a bigger lever. I can tell that the next thing I will need is to add a rear sway bar (no factory rear bar currently). It was planned eventually, but I think I will need it sooner than later now.

In the end, I'm very pleased with the conversion/upgrade. I will implement the same idea in my 71 Convertible during its build.

And if any of you are thinking of a similar idea, I'll say again that it's a wonderful addition to the 70-72 series A bodies. In my case, I was able to source a good used tank from a 70 GP @ our local salvage yard, and that ensured all of the fuel and vapor return lines were a perfect match.