no rpo codes in glove box and need to know my gear

[knightowl73]

Its my 92 gmc standard cab stepper with v6 and 5-speed. At 2500 rpm I'm doin 60-65 with 235-75-15 tires. Rear end has started howling so I've started my search. I do a lot of highway driving so wouldn't mind dropping rpms some, and having a reason to use first gear might be nice. I've been neglecting that gear, 2nd gets all the love. Would 3.42 be a goox gear for me or is it too much? Later might put 17s if i drop it so thought that might be ok. I think i have 4.10s out back. My 73 had that gear and topped out at. 65 without od and my truck has od in fifth
Am i on the right track?
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[75ChevyGuy]

Got the vin number? I may be able to do a search for it at work.

[knightowl73]

Originally Posted by 75ChevyGuy

Got the vin number? I may be able to do a search for it at work.

1GTDC14Z5NZ505297
Posted via Mobile Device

[75ChevyGuy]

GU4 = AXLE,REAR,3.08 RATIO 3.08R(GU4)
13D = TRIM COMBINATION CLOTH,LT GRAY CLOTH TRIM(13D)
13I = INTERIOR TRIM,LT SMOKE GRAY INTERIOR TRIM COLOR(13I)
1SC = PACKAGE-OPTION 03 (1SC)
1SZ = PACKAGE OPTION- (1SZ)
41U = EXTERIOR COLOR,PRIMARY (41U)
6WK = COMPONENT FRT LH COMPUTER SEL SUP (6WK) SUSP(6WK)
7WK = COMPONENT FRT RH COMPUTER SEL SUP (7WK) SUSP(7WK)
A31 = WINDOW,ELECTRIC OPERATED,SIDE ELEC SI WDO(A31)
A52 = SEAT,FRONT BENCH,3-PASSENGER FRT BENCH ST(A52)
A82 = RESTRAINT SYSTEM,HEAD(EXPORT) HD RST SYS(A82)(EXPORT)
AU3 = LOCK,SIDE DOOR,ELECTRIC ELEC S/D LK(AU3)
B32 = COVERING,FLOOR MATS,FRONT AUXILIARY FRT AUX FLR MATS(B32)
B3P
B85 = ORNAMENTATION,EXTERIOR,BELT REVEAL MOLDING BELT RVL MLDG(B85)
C5G = GVW RATING(5600 LBS) 5600 LB GVWR(C5G)
C60 = AIR CONDITIONER,FRONT,MANUAL CONTROLS A/C MAN CONT(C60)
C95 = LAMP,INTERIOR,ROOF COURTESY AND DUAL READING DM & READING LP(C95)
D45 = MIRROR,OUTSIDE,BELOW EYELINE(STAINLESS STEEL)(9.5 X 6) O/S STAINLESS STEEL MIR(D45)
E62 = BODY EQUIPMENT,STEPSIDE PICKUP BOX STEPSIDE PUBX(E62)
FWI = PLANT CODE FORT WAYNE, IN GM T&B FORT WAYNE,IN PLANT(FWI)
GQ1 = AXLE,REAR,STANDARD RATIO(MERCHANDISING OPTION) STANDARD RATIO R/AXL(GQ1)
GU4 = AXLE,REAR,3.08 RATIO 3.08R(GU4)
JB5 = BRAKE SYSTEM,VACUUM POWER DISC,DRUM VACUUM PWR BRK SYS(JB5)
K34 = CRUISE CONTROL,AUTOMATIC,ELECTRONIC CRCONT(K34)
K60 = GENERATOR,100 AMPERE 100 AMP(K60)
LB4 = ENGINE,(4.3Z),V6,EFI 4.3Z(LB4)
MG5 = TRANSMISSION,MANUAL 5-SPEED(GETRAG) GETRAG 5-SPD M/TRANS(MG5)
MM5
N33 = STEERING COLUMN,TILT TYPE TILT STRG COL(N33)
NA1 = EMISSION SYSTEM,LESS THAN 8500 LB GVW EMIS SYS(UNDER 8500 LB GVW)(NA1)
NA6 = EMISSION SYSTEM,ALTITUDE REQUIREMENTS ALT EMIS(NA6)
NK3 = STEERING WHEEL,SPORT,SOFT RIM,SIMULATED LEATHER SIMULATED LEATHER STRG WHL(NK3)
P06 = RING,WHEEL TRIM WHL TR RING(P06)
R9A
SLM
TFE
TR9 = LAMP GROUP,COURTESY LP GRP(TR9)
U16 = TACHOMETER,ENGINE TACH(U16)
U66 = SPEAKER SYSTEM,4,DUAL FRONT DASH MOUNTED,DUAL EXTENDED RANGE PACKAGE SHELF/QUARTER 4 SPKR SYS(U66)
UX1 = RADIO,AM/FM STEREO,WEATHER,CASSETTE,EQUALIZER,ETR,INCLUDES CLOCK STEREO AM/FM W/CASS & EQLZR(UX1)
V22 = GRILLE,RADIATOR(CHROME) CHROME GRL(V22)
V73 = VEHICLE STATEMENT - US/CANADA US/CANADA VEHICLE STATEMENT(V73)
VB3 = BUMPER,REAR STEP,INCLUDES IMPACT STRIP(CHROME) CHROME STEP BPR(VB3)
VG3 = STRIP,FRONT BUMPER IMPACT FRT BPR IMP STR(VG3)
VK3 = LICENSE PLATE,FRONT MOUNTING PACKAGE FRT LIC PLT MTG PKG(VK3)
VXS
XFN
YD3 = AXLE FRONT (BASE EQUIP) FOR SCHEDULING GVW PLATE FRT AXLE(YD3)
YD6 = SPRING,REAR(BASE EQUIPMENT) RR SPRING(YD6)
YE9 = CONVENIENCE PKG COMFORT & DECOR LEVEL #3 COMFORT & CONVENIENCE PKG #3(YE9)
YFN
Z88 = GMC TRUCK G M C(Z88)
ZFN = TIRE SPARE SPARE TIRE(ZFN)
ZQ2 = DRIVER CONVENIENCE PACKAGE DRVR CONVENIENCE PKG(ZQ2)
ZQ3 = DRIVER CONVENIENCE PACKAGE II(MERCHANDISING OPTION) DRVR CONVENIENCE PKG(ZQ3)
ZY1 = COLOR COMBINATION SOLID SOLID PAINT COMBO(ZY1)
Those are all your RPO codes. But it appears your have 3.08's out the back. Hope this helps!