Standard pushrod fits:
66-67 400CI

Length (In): 9.421 Inch
Ball Diameter (In): 0.312 Inch
End Type: Ball And Ball
Overall Length (In): 9.4450 Inch
Shaft Diameter (In): 0.312 Inch
Theoretical Length (In): 9.445 Inch
Center Oil Hole Included: Yes
Wall Thickness (In): 0.060 Inch