Subtle Difference Between Ductile Iron Rocker Arms intake vs exhaust?

RustyRatRod said
Those are not oil holes. Those holes are where the oil holes were drilled through the rockers from the factory. They didn't bother plugging them off, since the adjuster screws block them.

All but the last sentence is correct.
Those holes need plugged.

Reworking the 273 Adjustable Rockers | For A Bodies Only Mopar Forum
Reworking the 273 Adjustable Rockers