I was hoping someone knows some more information about specific RPO codes:
Z85- chassis package, increased capacity
Z82- trailer provisions, special equipment, HD
UY7- wiring harness, truck trailer, HD
VR4- trailer hitch, weight distributing platform

Does this equipment mean my Blazer has a pretty strong setup for heavy duty towing?

 

Here's my complete glove-box list. I don't have most of those codes. Seems clear that whoever originally bought it, wanted to do some towing.

AG1 -- ADJUSTER FRT S(ea)T POWER, MULTI-DIRECTIONAL, DRIVER (PWR adjust driver's seat)
AJ1 -- WINDOW TINTED DEEP, ALL EXCEPT W/S AND DRS (except Windshield & Front Doors)
AP9 -- NET CONVENIENCE, Cargo Net rear
AU0 -- LOCK CONTROL, ENTRY REMOTE ENTRY (Keyless Entry, doors & rear glass release on Key Fob)
AU3 -- LOCK CONTROL SIDE DR, ELEC (Power Door Locks)
AV5 -- SEAT FRT BKT, HIGH BACK
AXP -- VIN IDENT POSITION, MULTI-PURPOSE VEHICLE
A31 -- WINDOW POWER OPERATED, ALL DOORS
A78 -- ADJUSTER FRT ST BK MANUAL, DRIVER & PASS, RECLINING
B30 -- COVERING FLOOR CARPET, color-keyed
B84 -- MOLDING B/S EXTERIOR (bodyside molding black & chrome stripe)
C25 -- WIPER SYSTEM RR WINDOW, INTERMITTENT (& washer)
C3H -- GVW RATING 5,300 LBS
C60 -- HVAC SYSTEM AIR CONDITIONER FRT, MAN CONTROLS
DAY -- PLANT CODE MORAINE, OH, USA
DH2 -- MIRROR I/S FRT VAN LH & RH, ILLUM, WITH DUAL SUNSHADE (inside vanity mirrors on sun-visors)
DK6 -- CONSOLE ROOF INTERIOR (overhead console has compass & outside temperature in digital display, garage door-opener holder, sunglasses holder etc)
D48 -- MIRROR O/S LH & RH, REMOTE CONTROL, ELECTRIC, COLOR. (PWR adjust side mirrors, manually foldable, not body color unless they were later replaced with standard black ones)
D55 -- CONSOLE FRT COMPT, FLOOR (center console with catch-tray, coin-holder, cassette tape holder, cup holder & storage box/arm rest)
E3O -- RAPID DELIVERY SYS OLD ORDERS (-TRK ST)
E55 -- BODY EQUIPMENT END GATE
FE9 -- CERTIFICATION EMISSION, FEDERAL
FF6 -- ARM LH TORS BAR SPRING ADJ (E)
FF7 -- ARM RH TORS BAR SPRING ADJ (F)
GU6 -- AXLE REAR 3.42 RATIO
JM3 -- BOOSTER BRAKE, 240MM TANDEM, HIGH FLOW <---(This seems eroneous because the car has "PWR, FRT DISC, RR DRUM, CAST IRON, ANTILOCK, FRT & RR WHL" which matches code JM4)
K34 -- CRUISE CONTROL AUTOMATIC, ELECTRONIC
L35 -- ENGINE GAS, 6 CYL, 4.3L, CPI, V6, 90 DEG, HO
M30 -- TRANSMISSION AUTO 4 SPD, HMD, 4L60-E, ELECTRONIC
NF2 -- EMISSION SYSTEM FEDERAL, TIER 1
NG5 -- REGISTRATION EMISSION, CERTIFICATION, FIFTY STATE (50)
NP1 -- TRANSFER CASE ELECTRIC SHIFT CONT, TWO SPEED (push-button 4 wheel drive)
NP5 -- STEERING WHEEL LEATHER WRAPPED
N33 -- STEERING COLUMN TILT TYPE (tilt but not telescopic)
N40 -- STEERING POWER, NON-VARIABLE RATIO
N90 -- WHEEL 15 X 7, ALUMINUM CAST, 4.75 INCH BOLT CIRCLE
QCE -- TIRE ALL P205/75R15/N BL R/PE ST TL ALS
RSB -- (Something to do with Front Seat Restraints, Airbag?) or it's R5B which means all tires are Dunlop brand
RYJ -- SHADE CARGO AREA, RETRACTABLE
R8S -- CONTROL SALES ITEM NO. 68
R8T -- CONTROL SALES ITEM NO. 69
SLM -- SALES PROCESSING STOCK ORDERS
T61 -- LAMP SYSTEM DAYTIME RUNNING
UM6 -- AM/FM STEREO, SEEK/SCAN, AUTO REV CASS, CLOCK, ETR (Bass & Treble controls, no equalizer)
UP8 -- PROVISIONS, AM/FM STEREO, INSTRUMENTATION
U73 -- Antenna Fixed Radio
U89 -- WIRING HARNESS CAR TRAILER
VXS -- VEHICLE COMPLETE
V54 -- LUGGAGE CARRIER ROOF, PAINTED
V73 -- VEHICLE STATEMENT USA/CANADA
XCE -- TIRE FRONT P205/75R15/N BL R/PE ST TL ALS
X88 -- MARKET BRAND CHEVROLET
YCE -- TIRE REAR P205/75R15/N BL R/PE ST TL ALS
YC5 -- CONVENIENCE PKG DECOR LEVEL #5, LS trim w/ exterior appearance pkg.
YD3 -- AXLE (BASE EQUIP) FOR SCHEDULING GVW PLATE
YD5 -- SPRING FRONT BASE EQUIPMENT
YD6 -- SPRING RR, BASE EQUIPMENT
ZCE -- TIRE SPARE P205/75R15/N BL R/PE ST TL ALS
ZM8 -- SALES PACKAGE COMBINATION - ELECTRIC TAILGATE RELEASE/RR WINDOW DEFOGGER
ZQ1 -- CHASSIS PACKAGE SMOOTH RIDE
ZQ3 -- SALES PACKAGE DRIVER CONVENIENCE II, Tilt-wheel & Cruise Control
ZQ6 -- SALES PACKAGE DRIVER CONVENIENCE III, Power?
ZY1 -- COLOR COMBINATION SOLID
1SC -- PACKAGE OPTION 03
1SZ -- DISCOUNT OPTION PACKAGE
43U -- PRIMARY COLOR EXTERIOR, MAJESTIC TEAL (code 43U has been used for multiple colors over the years but apparently meant Majestic Teal from 1996 to 1999)
6WH -- COMPONENT FRT LH COMPUTER SEL SUSP (6WH)
64H -- TRIM COMBINATION CLOTH, BEIGE (H) (92)
641 -- INTERIOR TRIM LT BEIGE (I) (96)
7WH -- COMPONENT FRT RH COMPUTER SEL SUSP (7WH