GreyGhost,
Here is a list of the "GM General RPO Code Families" that may help you figure out some of the missing codes: :Twist
-AIR CONDITIONING AND HEATER_______C36 - C69
-AXLE, FRONT (RELATED)______________FL1 - FX2, F16 - F82
-AXLE, REAR (RELATED)_______________HO1 - H99, HA1 - HY9
GO1 - G99, GA1 - GY9
-BRAKES____________________________JS0 - J99, JA1 - JY9
-BUMPER COMPONENTS_______________V30 - V99, VN1 - VY9
-DEFOGGER - REAR GLASS_____________C47 - C50
-ELECTRICAL, CHASSIS________________UO1 - U99, T60 - T99
-ENGINE (RELATED)___________________KO1 - K99, KA1 - KY9
LO1 - L99, LA1 - LY9
-EXTERIOR ORNAMENTATION____________BVZ - BY1, B51 - B99
-FUEL, EXHAUST AND EMISSIONS________NO1 - N29, NA1 - NN9
-GLASS______________________________AO1 - A33, AA1 - AA9
-INTERIOR ORNAMENTATION_____________BB8 - BV9, B18 - B48
-LAMPS______________________________C71 - C97
-LOCKS______________________________AU3 - AU6
-MIRRORS, BODY______________________DD4 - DK5, D28 - D78
-MOULDINGS AND EXT EMBLEMS__________B71 - B94
-RADIATOR AND GRILL_________________VO1 - V29, VA1 - VM9
-RADIO RELATED______________________UK1 - UY8, U56 - U96
-ROOF, ORNAMENTATION AND TRIM_______CA1 - CC3, C01 - C10
-SEATS, SEAT ADJUSTERS_______________A34 - A81, AE5 - AV7
-SPRINGS____________________________6AA - 6ZZ, 7AA - 7ZZ
8AA - 8ZZ, 9AA - 9ZZ
-STEERING (RELATED)__________________N30 - N59, NN1 - NY9
-STRIPES, BODY DECOR_________________DX1 - DY6, D84 - D99
-SUSPENSION_________________________F40 - F99, FN1 - FY9
-TRANSMISSION_______________________M01 - M99, MA1 - MY9
-WHEEL AND TIRE______________________N60 - N99, P01 - P99
PA1 - PH9, PW1 - PY9
Q01 - Q99, QA1 - QY9
R01 - R30
-WIPER/WASHER/WINDSHIELD____________CD2 - CE4, C18 - C25