Does your car have the vapor separator on the shock x-member? If it does, you need the 72-74 style tank that has the four tubes coming out the FRONT side of the tank. Those tanks DO NOT have an extra expansion tank inside them...even from the factory. That is the job of the vapor separator on the shock x-member.
If your car has the large tube in the trunk on the passengers side, then you need the 71 style tank that has the tubes sticking out the SIDE of the tank.