The interior color code of the Chevelle is coded as a single letter.

BBlueJSaddle VinylRGray Green
DRedLBlack VinylTTurquoise
EBlack Cloth/Vinyl - Black Vinyl **PGold Vinyl (Opt.)UBlue Vinyl (Opt.)
GGoldQBlack & White VinylXTeal Vinyl
KSuspect Parchment vinyl bench/bucket w/black trim *    

* Note this warranty card has the interior trim color as letter "K." To date this code has not been found in any other documentation besides warranty cards. On two warranty cards (Fremont & Kansas City) with known interior trim code, this "K" appears with parchment vinyl bench and bucket seats w/black trim. The letter "K" also appears on a third Kansas City POP but no confirmation on the interior code.
** E has been found on 13837 SS396 sport coupe and all SS396 Chevelles came with full vinyl seats