It's a small hole in the rear oil galley plug. Mopars have been known to have poor lubrication in and around the dist drive gear. Not really "poor" but slightly insufficient in some motors. Either way if you drill a very small hole (.025) in the center of the plug before you install the plug you'll get all the oil you need on the drive gear. It's a pretty cheap and easy oiling mod that will ensure a long life for your dist drive.
treblig