I had my '34 water pump rebuilt; it leaked quite badly after the reinstall, and I sent it back for warranty work to Arthur Gould Rebuilders. In the meantime, I obtained another '34 water pump that was said to have been rebuilt by a reputable rebuilder in the 90s. Side by side, it seems like the two pumps have one difference - there is a hole over the bearing, on one pump it is sealed with a metal plug and on the original leaky pump this metal plug is missing. Some folks I've consulted indicated that some pumps have such an opening and it's designed to be left open. Does anyone have any information about this - I've included a picture.
Refer this question to the 34 tech person.