OK, now I have two vehicles that I know have the factory grills. My '69 and my brother's '70. Here is the differences:
Here is a closeup of a factory 69 grill between the marker lights and headlights:
Here is the factory 70:
the other side, 69:
The other side 70:
The egg-crate part, 69:
The egg-crate part, 70:
A closer look at the 'lines' in the '70:
As it is plain to see, 69 grills have lines out to the bezel, and a solid patterned egg-crate behind (in gray).
70s have lines that end just past the marker light and the egg crate has the same basic pattern, but there are recesses that don't get chrome, that give the appearance of 'lines' in the grill. The chrome bezels on the '70 are factory too.
Both of these pickups were made in Freemont, CA.