[Mr70]

1970 L-78 equipped Chevelles were only assembled in the first 100 days of production at ALL 6 assembly plants.They were phased out for the new LS-6 engine after late November 1969.Michigans Flint plant only built Chevelles in September 1969,and then stopped from Oct.1st 1969 to Jan.31st 1970, before starting up again in February 1970.This car was assembled April 1970,2nd week so if it's what he says it is and the tach is authentic to this vehicle,it would have had to have been an LS-6 originally...Unless he or anyone else can provide past history to suggest otherwise.
The rearend code could be a clue to true it's heritage,among other items.
Interesting that it's a Flint build.