Rear expansion plug of rear cam shaft question.

I have only ever seen the "cup-style" plugs; and have never seen these factory-staked.
I thought the fit was rather loose too, so always glue it in with Indian-Head shellac. So far I haven't had any pop out. It is for this reason that I never leak-test the assembled engine with more than 4psi; if that plug ever popped out I would be a very unhappy guy.And I bet my boss would be even unhappier.