The 2 wire solenoids are for cars with HEI distributors. The outside wire is no longer needed to supply a cranking-time-only 12 volts to the distributor because HEIs always use 12. Points based distributors normally use 6.6 volts. So basically you got a starter with the wrong solenoid since your original had 3 wires. Either switch the old & new solenoids or go back to your parts store and tell them you have a points based distributor and need all 3 terminals.
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