Lee is correct. On the inside - regular ol' pop rivets: typically 1/8" in diameter. Some of the interior rivets were bucked rivets (domed head, no hole) and would be replaced with Olympic rivets. The exterior was mostly bucked rivets as well and since you can't usually get to the backside of the rivet, you'll need Olympics to replace them.
Hope this answers your questions.
4CU 2699 / AIR 10 / TAC AZ-1
I'm haunted by aluminum.
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