Anyone know if there was a correction made along the way since the book has two different codes; PLL10c-in dark gray... and PLL10d-in light gray. One value is $10-$20 and the other $75-$120 -- (in 2006)... The 10d does note new condition, though... but why two codes for an unused and used chip I wonder... Big $$$ involved... There's even a split color difference illustration in the book with each split having its own code.
The manufacture date is 1976...?