Dual point distributor ID question

Yes, I just checked the 1966 FSM, and the specs are identical between it and the 2642242 which is what is listed for 1967 (and is in my 67 FB). But the # is listed for 1966.

So, why the different part number, is my question? Whatever...
My book shows the same part number for 66 and 67.
2642405 is with CAP Did you read my post #5?