What parts are you talking about? There are 2 different tanks that go in a 69.5/70. One tank without a fancy evap vent on the top (California emissions) and one with.
The 1970 system consists of a sealed fuel tank filler cap, an expansion area at the top of the gas tank, a combination vapor separator and expansion tank assembly, a 3-way vapor control valve, a carbon canister located in the engine compartment which stores these vapors, and the hoses which connect this equipment. The 1971-77 system consists of a special vacuum/pressure relief filler cap, an expansion area at the top of the fuel tank, a foam-filled vapor separator mounted on top of the fuel tank, a carbon canister which stores fuel vapors and hoses which connect this equipment. On both systems, the carburetor fuel bowl vapors are retained within the fuel bowl until the engine is started, at which point they are internally vented into the engine for burning. As the gasoline in the fuel tank of a parked car begins to expand due to heat, the vapor that forms moves to the top of the fuel tank. The fuel tanks on all 1970 and later cars are enlarged so that there exists an area representing 10-20% of the total fuel tank volume above the level of the fuel tank filler tube where these gasses may collect. The vapors then travel upward into the vapor separator which prevents liquid gasoline from escaping from the fuel tank. The fuel vapor is then drawn through the vapor separator outlet hose, through the 3-way vapor control valve (1970 only), then to the charcoal canister in the engine compartment.
Are you talking about any raised areas built into the sheet metal of the tank? If so, I would say that they are there to provide strength to the overall shape of the tank.
Yes that is what I ment so its only for strength IS there anything inside the tank? what holds in the fuel sender unit it thingy
The fuel sending unit is held in with the bezel on the outside of the tank, nothing is connected to the inside.
