As a newbie, upon receiving a vintage drum I purchased, I looked forward to carefully removing the drum's hoops and heads, and looking for the DATE STAMP!!!! I believed they were placed arbitrarily by whatever orientation the drum was handed to the "DATE STAMP MASTER"...haha. This is not the case. There was order to this process. Knowing that many of the batter and reso heads would be opaque and that current and future buyers would likely want to see the date stamp, MOSTLY the "DATE STAMP MASTERS" were instructed to place the stamp inside the shell opposite the VENT HOLE IN THE BADGE so that without any disassembly of the drum, the date stamp could be viewed. In my own experience, this holds true more than 80% of the time.
Pass this knowledge on in good health and prosperity, my friends!
BECAUSE OLD DRUMS RULE