On a side note they got rid of the 4 line ECS used in 70/71 in 72 because it vented into the crankcase. In 72 it vents into a charcoal canister. I have heard rumors of gas fumes in the crankcase igniting and popping valley pan seals and valve covers. I have never seen it but I have heard rumors.
Actually they didn't get rid of it. In 72-up the 4 lines are on the front of the tank and go to a small vapor tank mounted up on the shock cross member. Also in 72 the charcoal canister was Added to the system.
