Those are called ECLs for exception control letter. Don't waste your time. You would need hundreds of window stickers to research them and at this time I do not believe all meanings will ever be known. I've been charting '69 ECLs for years. Some are easily understood, some options have several ECLs for no obvious reason. N40 power steering has 11 so far, Z22 rally sport has 15. JL8 has 2; one for 3:73, one for 4:10. Most engine options are AA for manual, AB for auto. Interiors also used them; I have 9 so far for midnight green standard. No idea what they mean - otherwise identical cars may have different ECLs.