The side of block core plugs (5) are originally GM# 663032 - Plug, cylinder block 1-1/4" OD (cup style).

You can get Dorman 555-023 which is a 1-1/4" OD cup style "steel" core plug, or Dorman 565-023, which is a 1-1/4" OD cup style "brass" core plug. wink
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Last edited by Gdads51; 06/13/2026 9:37 PM. Reason: fix typos
~ Dan
1951 Chevy 3 window 3100
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