As much as I can find out using the RPO finder posted by another member and looking at the RPOs for '05, '06, and '07. It seems Chevy had some carry over. 521 and 522 are either unknown or a little squirrelly... When i worked at a dealer they had one or two guys that ordered cars, i don't know how they did it, I mean codes changed all the time... I bet the factories update the codes as option change though out the production cycle and the dealers just take what they receive, most of the vehicle will be as ordered but not exactly....
AG1 Seat adjuster, driver power
AG2 Seat adjuster, front passenger power
AJ1 Glass, Solar-Ray deep tinted
AJ7 Air bags, side-impact, driver and right front passenger
AL0 Indicator Inflatable Restraint, Front Pass/Child Presence Detector
AN3 Seats, front leather seat inserts
AU0 Keyless entry, remote
AU3 Control, Side Driver, Electric
AXP NT Position, Multi-Purpose Vehicle
A31 Power Operated, All Doors
BVR Running Board, Side, Tubular, Stainless Steel
B30 Floor covering, color-keyed carpeting
B37 Floor mats, black, rubberized vinyl
B41 Cargo Area Floor Mat
CF5 Electric Sliding Sunroof
CJ2 Air conditioning, dual-zone, automatic
C49 Defogger, rear-window, electric
C5W GVWR, 7000 lbs. (3175 kg)
DF5 Inside rear view auto-dimming
DH6 Visors, driver and front passenger illuminated vanity mirrors
DK8 Console, Roof Interior, Deluxe
DL3 Mirrors, outside heated power-adjustable, power-folding and driver- side auto-dimming
DT3 Rear Stowage Compartment
DT4 Smoker's Package, Cigarette Lighter & Ashtray
DO7 Console, floor
EN4 Cargo cover, rear, rigid
EVA VT, Evaporative Emission Requirement
FE9 Emissions, Federal requirements
FK3 Arm, RM RH Torsion Bar Spring Adjust DJ (B)
GU6 Rear axle, 3.42 ratio
G80 Differential, locking, heavy-duty, rear
JF4 Pedals, power, adjustable
JH2 Brake Hyd Power, Disc/Disc, 7,200 LBS 1016
JL4 StabiliTrak
KG3 Alternator, 145 amps
KUP Throttle Control Electronic
KO5 Engine block heater
K34 Cruise control
K47 Air cleaner, high-capacity
L59 Engine, Vortec 5300 V8 SFI Flex-Fuel
MSL Silao, Mexico Plant
M30 Transmission, 4-speed automatic
NP5 Steering wheel, leather-wrapped rim
NP8 Transfer case, electronic Autotrac
NT8 Emission System Federal, Tier 2 A 211
NZZ Skid Plate Package
N89 Wheels, 4 - 17" x 7" (43.2 cm x 17.8 cm) aluminum
PDA Sun and Sound Package, includes (U2K) Sound system feature
QJM Tires, P265/70R17, on-/off-road, White outlined-letter
R4Y Tire Brand All GOODYEAR
R6P OL Sales Item No. 15
R9N OL Sales Item No. 89
R9U OL Sales Item No. 95
SAF Tire carrier, lockable outside spare
SLM Sales Processing Stock Orders
TR3 Grill Radiator, Body Color, W/Chrome Emblem
T96 Fog lamps, front round
UC6 Sound system, Extended Range AM/FM stereo with 6-disc CD changer
UE1 On Star
UG1 Universal Home Remote
UJ6 Tire pressure monitor
UK3 Steering wheel controls, mounted audio, Driver Information Center and cruise controls
UK6 Sound system feature, rear audio controls
UQ7 Sound system feature, Bose Premium speaker system
U2K Sound system feature, XM Satellite Radio
VB3 Bumper RR Step, Chrome, Impact Strip
VG3 Bumper Front Impact Strip
VR4 Trailer Hitch Weight Distributing Platform
VXS LE Complete
V1K Luggage rack center rails
V54 Luggage rack, roof-mounted, Black
V73 Vehicle Statement USA/CANADA
V76 Recovery hooks, front, integrated into front bumper
WBH Without Body Hardware
XJM Tire Front P265/70R17-113S WOL R/PE ST TL OOR
X88 Market Brand Chevrolet
YD3 (Base Equipment) For Scheduling GVW Plate
YD5 G Front Base Equipment
YD6 G RR, Base Equipment
YE9 Convenience Package Comfort & Decor Level #3
YJM Tire Rear P265/70R17-113S WOL R/PE ST TL OOR
ZGC Tire Spare P265/75R16-114S BW R/PE ST TL AT
ZM9 Package Comfort & Convenience
ZY1 Color Combination Solid
Z71 Suspension Package, Off-Road
Z82 Trailering equipment, heavy-duty
1SL Package Option 11
1SZ UNT Option Package
41U Indicator Low Fuel
521 No Match
522 Trim Combination Leather, Light Neutral (2) (96)
OR Trim Combination Leather, Medium Neutral II (2) (9
6XM Component Front Left Hand Computer Selected Suspension
7XM Component Front Right Hand Computer Selected Suspension (7XM)
BC/CC= Base Coat Clear Coat Color Number U 8555 (Gloss Black) 522= ?