As it's a Concord, not a Concorde, I'm guessing your talking a mass market Japanese bike from the early 70's. Which means an English threaded BB. Check your fixed cup, it should be left handed thread. If so, truck on with no worries.
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Syke
“No one in this world, so far as I know — and I have searched the records for years, and employed agents to help me — has ever lost money by underestimating the intelligence of the great masses of the plain people. Nor has anyone ever lost public office thereby.”
H.L. Mencken, (1926)