Charcoal Can Fans, should I?

IIRC.......'70 and older have a vented fuel neck, and nothing on the tank. '71 has the ECS system with multiple lines coming off the tank and the expansion chamber in the trunk (I believe 70 california cars had this as well). Neither of these had a charcoal canister. In '72, they had a vent line coming from the tank terminating at a charcoal canister that has a provision for distributor vacuum. After '72, same tank config with one vent line terminating at the charcoal canister (No distributor vacuum connection on canister).