For 1965 (Pontiac) the build manifest gives the handy decode on the document itself.
I did a quick cursory check and many of the codes seem to be the same for 1964 and 1965, so this might get you started.
The codes are read using the box number and then the specific option content, ie:
Box 38 code 2 = GTO
Box 39 code 8 = manual antenna
If the number is higher than any of the individual choices it means they have been combined (they add up),ie:
Box 42 code 7 would be W/S Washer (1) + Dual Exh Ext (2) + Inst Panel Pad (4) = 1 + 2 + 4 = 7
etc
K
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'63 LeMans Convertible
'63 Grand Prix
'65 GTO - original, unrestored, Dad was original owner, 5000 original mile Royal Pontiac factory racer
'74 Chevelle - original owner, 9.56 @ 139 mph best
http://www.superchevy.com/features/s...hevy-chevelle/
My Pontiac Story: http://forums.maxperformanceinc.com/...d.php?t=560524
"Intro from an old Assembly Plant Guy":http://67-72chevytrucks.com/vboard/s...d.php?t=342926