Ahh! Reminds me of my Navy Life. "To grease or not to grease?? That is the question."
Large motor frames aways seemed to have a grease passage into the bearing seat area. However, the mfg would only install a zerk if the motor had open bearings (common in motors 40 years ago). Later, as sealed bearings became common, they put plugs in the threaded openings.
Over time many/most of the navy motors went into for cleaning and overhaul. Sealed bearing replaced any open bearings still installed and the service facility pluged the grease passage to prevent damage to the sealed bearing and motor by pumping in grease.
However, the maintanance cards still called for greasing the motor every year or so. So the sailor would reinstall the grease zerks and fill the motor with much un-needed grease.
Bottom line, most large frame motors will have grease passage, however the only way to determine if it has open bearings would be to pull the need bells and see what type of bearing it has. No need to remove the bearing since you should be able to see the seal on the exposed side of the bearing.