The 289 street tank was mounted right behind the driver under the rear cowl area. If you were to look into the trunk--look up above the spare tire tray and you will see an aluminum interior panel. Behind that panel, (and under the rear cowl), is the gas tank.
The FIA cars used the same tank, along with an extra tank which mounted right behind the 1st tank. That tank is clearly visible on FIA cars.
David
