[Gearhead999]

Well.........darn near every vehicle had a road draft tube for crankcase evacuation.

You have to remember that when the piston goes up it makes compression. Well, when it goes down it displaces air and volume in the crankcase. This positive pressure and fumes have to go some where. So they had a tube that vented it to the outside. Some engines had a tube from the valve cover and others had the tube from the intake manifold. This vented the crankcase.

Then the PCV came out, which vented the pressure/fumes to the base of the carb.

Hope, that explains it for you.