So what I did was to suggest an obvious and *unmentioned* option for everyone to consider. The OP didn't mention wanting a toolbox nor more space.
Mounting a stock auxiliary tank is a *lot* easier than the between the rails tank.
My mention of the tank being safe was due to the *fact* that many people have been scared away from in-cab tanks.
But the responses that tried to do little more than attack my idea.
So why does anyone try to post helpful suggestions?

 

I put a mustang unit where my spare tire used to be.

 

To each his own amigo. All ideas are welcome in a 'brainstorm' session, which is part of what the forum is for. ie, the sharing of ideas. Yours is the obvious and easiest change, and what the factory chose to do in '67 -'72, but that is not the end of ideas. For instance, some like the bench seat, some like buckets. The factory chose a bench. Perhaps, its because they always did it that way. I am sure that nothing personal was intended, by the subsequent comments. All are trying to help, as few of us know it all.. and certainly not I.

Baja

 

...how do I delete a post when I goof?

 

I'm looking to try exactly what you suggested, but in a '64 2wd.. The auxiliary tank won't work in a 4wd, and only was an option on 2wd trucks.

 

I don't think anyone was attacking your idea, it's a good one! That's the thing with online chatting like this, it's easy to misunderstand someone. So, keep posting up ideas, we're all open to them!

 

I have seen a '71 4x4 with dual saddle tanks. Guy was selling it as a parts truck in my old neighborhood.

 

The Auxiliary Tank is different that saddle tanks; the auxiliary mounts inside the frame, mid-ship, and holds 20-25 gallons. Usually came on Camper Specials, but was an option for 2wd, and is still available new for a decent price.

 

Saddle tanks are no safer than in the cab tanks, and may even be a bit more dangerous, as are only protected by the thin sheet metal of the bed. They also require cutting a hole in the side, and installing a small aux door. For me, safety was not the motivation for moving my in cab tank, added room for a behind the seat tool box was my focus. In Baja, I like carrying some tools, as AAA cannot come to your rescue, and self reliance is paramount to survival in remote locations.

Baja

 

My motivation was safety. It's bad enough that when I'm riding my bike that my junk sits on top of the gas tank, I didn't like the idea of driving my truck and my back resting against the gas tank there.

 

3X on keep posting Millam. Just like texting, posting can come across different than intended. These guys weren't disrespecting you or your idea.
As a side note, my 68 C.S. has the aux tank you suggested. And has that big O' protective cover over the filler neck. Which takes away from bed volume. Tomahawk's idea of fuel filler placement is super cool. 2X Baja. You oughta check out his tank thread.

 

Been there Jeff, and am a follower of Gavin's lead. His is the most savvy solution, to tank-between-frame rails, I have seen. If I can, I will incorporate his fill pipe design, in my truck. Photos to follow, when I get home to Baja. Dodging Tornadoes, floods, and sink holes in Texas at the moment. So far, so good, but more throughout the week are forecast. Keep your fingers crossed for me..

And Millam, 2x on Jeff's post. Keep on post'n..

Baja