[Mr70]

I've never seen a factory equipped 1970 L-78 Chevelle with a factory installed (CO) dual snorkle.
As far as I know,it wasn't possible to get a dual snorkle on a 1970 L-78 equipped Chevelle while being assembled.
That BB Dual came out later on during 1970,while the L-78 engine,which was only available for roughly the first 90 days of production,had long been discontinued on the Chevelle.
Open element (SS) or Cowl Ind.(DG) were it's only possibilities.