A pin punch is a relatively small diameter punch. If you grind the tip at an angle, it can be used as a sort of chisel.
LINK

The pictures look like someone installed a cup style plug rather than an expanding welch plug.

Here's a pic of the different types of expansion plugs, I think you're looking at the one I circled.
Attachments
Expansion Plug types.jpg (32.12 KB, 65 downloads)

Last edited by klhansen; 06/19/2026 1:15 AM. Reason: added picture
Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.