g.m.c blower question about oil hole

Where is the oil hole that needs to be pluged? I'm converting a 371 and word has it that if left unpluged the motor can injest oil, so is that hole under vucum? can someone post a pic of the hole please? there are a couple good tech posts about the conversion but no pix of the hole in question. Thanks Von Doc

 

In original Diesel application of the 71 series blowers, there are feed holes in the end plates that allow engine oil to lubricate the bearings and gears.

When doing the conversion, you will likely be using sealed bearings in the rear, so you don't need to address those. In the front, they must be plugged.

Turn the blower over. and look in the case, behind (inside) the plate. You should see a hole, or two that go into the oil galley for gears.

This is an oil hole on a 4-71 I have on the shelf, yours should be similar:

 

Thank You Gimpyshotrods, from the looks of it the oil holes are not under vaccum, but I could see where things could get messy and the gear oil could leak out if unplugged, this is not My 1st blower but it is the 1st I've converted Myself. Thanks again Von Doc