They put the gas tanks in the cab way back in the 30's and 40's also.
Chevy took it out on one model year... late 1940's... I forget which year, but the 1947-1953 body style(advance design as they are referenced).
They found that with the roads back then... this was pre interstates and paved roads everywhere... they found that road debris and working in woods, fields or a job site would damage the gas tank and make it leak. The owners of the trucks told 'em to put it back in cab so they would stop having problems.
The tank was in the cab until sometime in the 1970's.
I've had my 1965 c10 since April 2003 with the tank in the cab. I've seen some photos of wrecked trucks like mine and my feeling is, if the gas tank punctures, I'm probably already dead from the impact.
The old mechanics and guys with these trucks when they were new have told me that as long as you keep the seals, fittings and hoses in good shape, you should not have any problems.
About the only real reasons for taking it out:
having more space for storage behind the seat.
you are going to run a larger fuel tank.
you current in cab tank is junk and you want to do the above or the cost is less.
I saw a truck a fella had, it was a '55-'57 with the tank out of the cab and he built these really nice shelves in there with a lip on each shelf to hold stuff in place. He had his detailing stuff, oil and basic tools back there.
Some people install stereo systems back there, others use it to stash tools or things related to the primary use of the truck.
-W
