Tom I'm restoring a 69 L-89 corvette and it's body build is 8-28-69. I also have seen later L-89 vette's. It also could be a L-88. 074's came into production in the 21000 serial # range. Which was earlier than this but it could have been a left over.
Rich.
it may be worth poping a head off to look for High dome pistons...or pulling off the pan to see some dimpled rods
