I recently picked up a numbers-matching 68 L36 project car. It is mostly original and undisturbed except for a few minor things. Build date is May 2. The alternator (a 693) date is 6F26 (26 June 1966) which I assume is much too early for a 1968 car. I can see how perhaps the alternator might have been replaced with one from 1969 (or later) but an earlier date? I see lots of 65-67 alternators on Ebay . . . but none from 68. Any thots?

You could check with the NCRS to see what their ruling would be on it. 

1973 L-82 4 spd