differential help

[Jayson Newland]

alright so i guess first off ill start with i have a 99 silverado 4wd. the rear differential started making a clunking noise when i let off and the truck slows down, more noticeable at lower speeds. i first tought it was a u joint until i crawled under. the pinion rocks back and forth a little bit. today i hauled a trailer for my buddy and after dropping the trailer on the way home it would clunk real hard after beginning to accelerate. so i guess my question is what is a good replacement differential from the stock gt4 g80 (locking 3.73)? how do i know what size the rear end is as far as like a 8.5 or 10.5 etc.and the spline count and such without taking it apart. it is my daily driver. i figure i may as well ugrade while ive got it apart. i do tow a bit. the truck is lifted 3" on 325/65/18 bfg at if that needs to be known. thanks in advance. jayson

[RyanbabZ71]

Are you sure its the diff and not the slip yoke? I would try greasing the slip yoke first that is cheap and easy to do.

[Jayson Newland]

yeah im sure its the pinion.

[Jayson Newland]

middle of 2014 i lost the driveshaft runnin about 75mph on my way to nashville. had to get a custom driveshaft made for it and i got a new yoke for it as well as new tailshaft seal. figured i might as well have. so it should still be good and dandy.

[Jayson Newland]

heres the build sheet.

1GCEK19V8XE204417

Vehicle: SIL 1500 EXT CAB STD BOX
Year: 1999
Build Date: 1999-04-08

 

RPO Description

M7 RADIO,AM/FM STEREO,ETR,INCLUDES CLOCK STEREO W/CLK(UM7)

UQ5 SPEAKER SYSTEM,4,DUAL FRONT DOOR MOUNTED,DUAL EXTENDED RANGE QUARTER MOUNTED 4 SPKR SYS(UQ5)

VG3 STRIP,FRONT BUMPER IMPACT FRT BPR IMP STR(VG3) VXS VEHICLE - COMPLETE

V43 BUMPER,REAR STEP(PAINTED) PAINTED STEP BPR(V43)

V73 VEHICLE STATEMENT - US/CANADA US/CANADA VEHICLE STATEMENT(V73)

XNK Unknown

X88 MARKET BRAND CHEVROLET CHEVROLET(X88)(EXPORT)

YD3 AXLE FRONT (BASE EQUIP) FOR SCHEDULING GVW PLATE FRT AXLE(YD3)

YD6 SPRING,REAR(BASE EQUIPMENT) RR SPRING(YD6)

YNK Unknown

ZNK Unknown

ZY1 COLOR COMBINATION SOLID SOLID PAINT COMBO(ZY1)

Z83 CHASSIS PACKAGE,SOLID SMOOTH RIDE CHAS PKG(Z83)

1SA PACKAGE-OPTION 01 (1SA)

1SZ PACKAGE OPTION- (1SZ)

11U EXTERIOR COLOR,PEWTER MET (11U)

12C TRIM COMBINATION CLOTH, GRAPHITE © (92) CLOTH TRIM(12C)

12I INTERIOR TRIM GRAPHITE (12I)

6WY COMPONENT FRT LH COMPUTER SEL SUSP (6WY) SUSP(6WY)

7WY COMPONENT FRT RH COMPUTER SEL SUSP (7WY) SUSP(7WY)

AE7 SEAT,FRT SPLIT,EASY ENTRY EASY ENTRY SPLIT F/SEAT(AE7)

AM7 SEAT,REAR FOLDING RR FLDG ST(AM7)

C60 AIR CONDITIONER,FRONT,MANUAL CONTROLS A/C MAN CONT(C60)

C7H Unknown

DE2 MIRROR,OUTSIDE,LH & RH,DIRECT CONTROL,FOLDING,PAINTED O/S MIR(DE2)

EVA TEST DVT, EVAP EMISSION REQUIREMENT EVAP EMISSIONS REQUIRED(EVA)

E63 BODY EQUIPMENT,FLEETSIDE PICKUP BOX FLEETSIDE PUBX(E63)

FE9 FEDERAL EMISSION CERTIFICATION FED EMIS(FE9)

FK2 ARM,TORSION BAR,SPRING ADJUST,LH TORS BAR SPR ADJ ARM(FK2)

FK3 ARM,TORSION BAR,SPRING ADJUST,RH TORS BAR SPR ADJ ARM(FK3)

GMC PLANT CODE PONTIAC, MI, GM T&B PONTIAC,MI GM T&B ASSEMBLY PLANT(GMC)

GT4 AXLE,REAR,3.73 RATIO 3.73R(GT4)

G80 AXLE,REAR,POSITRACTION,LIMITED SLIP POSITRACTION L/SLIP R/AXL(G80)

JC5 BRAKE VAC POWER, 4 WHL DISC, 7,200 LBS BRK VAC PWR DISC(JC5)

K68 GENERATOR,105 AMPERE 105 AMP(K68)

LR4 ENGINE GAS, 8 CYL, 4.8L, MFI 4.8V(LR4)

M30 TRANSMISSION,AUTOMATIC 4 SPEED,4L60E,ELECTRONIC 4-SPD A/TRANS(M30)

NF2 EMISSION SYSTEM,FEDERAL,TIER 1 FED EMIS SYS(NF2)

NP2 TRANSFER CASE,MANUAL SHIFT CONTROL,TWO SPEED MAN SHFT TRFER CASE(NP2)

QNK Unknown SLM SALES PROCESSING - STOCK ORDERS