Dave - Check out this previous thread on the GMC 6 front and rear freeze plugs and camshaft bearing plug. Was in response to a GMC 270 question, but as Bill says, they are the same.

My part numbers came from an earlier GMC Parts Books resource than Bill's part number, but as far as I know they are the same plugs. After seeing Bill's provided GM#, I found it listed in the 1963 GMC Master Parts Book. This reference doesn't provide dimensions, but the same GM# is listed for Chevy applications and one description listed the cam bearing plug dimensions as "rear brg. cup (1-63/64")". For whatever reason, my previous search didn't turn up Bill's part number. headscratch

Did you need info on the block side "frost plugs" too?
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~ Dan
1951 Chevy 3 window 3100
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