AJ1- Deep window tent RR
KC4- Engine oil cooler
GT5- 4.10 gears
LQ4- 6.0
M32- AT 4 speed HMD 4L60E HD
NP3- AWD transfer case
NYS- 4 wheel steer
Y91- Luxury edition
Z82- Trailer provisions special equipment HD
Z88- Brand GMC

The rest of the RPO's are not that interesting to me.