rear axle ratio RPO

[Madkaw_16]

Quote: Originally Posted by ss350

Just wanted to update this sticky.

On 98-01 Blazers 7 5/8 ring gear, 28 SPLINE, the length of the axle is 26 3/8".

On 98-01 S10/S15 Trucks 7 5/8 ring gear , 28 spline, the length of the axle is 26 5/8". I had to learn this the hard way.

Are you sure this is right? It could be, but, i put a 96 pickup axel in mine and it was 1/2'' narrower.(shorter)

Just wondering

[Golana]

my axle code says GV4...
on the rpo decoder, it says i have freaking 5.42 gears!!!...

that cant be right...

complete list of my codes:

AJ2 SEAT RR , "FOLDING, JUMPSEAT"
ANL SALES PACKAGE , "AIR DEFL, FOG LP"
AV5 SEAT , "FRT BKT, HIGH BACK"
A28 WINDOW RR , "FULL WIDTH, SLIDING"
A78 ADJUSTER FRT ST BK , "MANUAL, DRIVER & PASS, RECLINING"
B30 COVERING FLOOR , CARPET
C42 HVAC SYSTEM , "HEATER, OUTSIDE AIR, DELUXE"
C5T GVW RATING , "4,200 LBS"
E63 BODY EQUIPMENT , FLEETSIDE PICK-UP BOX
F51 SHOCK ABSORBERS , "FRT & RR, HD"
GMC PLANT CODE , "PONTIAC, MI, USA"
GQ1 AXLE , STD RATIO
GV4 AXLE REAR , 5.428 RATIO
JM3 BOOSTER , "BRAKE, 240MM TANDEM, HIGH FLOW"
LB4 ENGINE, GAS, 6 CYL, 4.3L, TBI, V6, 90 DEG
MM5 MERCHANDISED TRANS , MAN 5 SPD PROVISIONS
MY2 TRANSMISSION , "MAN 5 SPD, NVG, 85MM, 4.01 1ST, O/D"
NA5 EMISSION SYSTEM , "FEDERAL, TIER 0"
NQE FUEL TANK , "76L, 20 GAL, SINGLE"
N40 STEERING , "POWER,"
P06 TRIM DISCS , WHEEL
QPP TIRE ALL , P225/60R16-97V BW R/PE ST TL AL3
R6S CONTROL , SALES ITEM NO. 18
R7K CONTROL , SALES ITEM NO. 36
SLM SALES PROCESSING , STOCK ORDERS
UA1 BATTERY , "HIGH CAPACITY, WET"
UM6 RADIO , "AM/FM STEREO, SEEK/SCAN,"
UP8 RADIO , "PROVISIONS, AM/FM STEREO, INSTRUMENTATION"
U73 ANTENNA , "FIXED, RADIO"
VXS VEHICLE , COMPLETE
VY3 FLEET PROGRAM , "OPTION PACKAGE INCENTIVE, PACKAGE B"
XFP Unknown RPO Code
X88 MARKET BRAND , CHEVROLET
YD3 AXLE , (BASE EQUIP) FOR SCHEDULING GVW PLATE
YD5 SPRING FRONT , BASE EQUIPMENT
YD6 SPRING , "RR, BASE EQUIPMENT"
YPP Unknown RPO Code
ZJ7 WHEEL,SPL HUB CAP & TR RING
ZM7 Unknown RPO Code
ZPP Unknown RPO Code
ZY1 COLOR COMBINATION , SOLID
Z31 IDENTIFICATION , PRICE SHEET ADVANCE
Z49 EXPORT , CANADIAN MODIF MANDATORY BASE EQUIP
1SA PACKAGE , OPTION 01
1SZ DISCOUNT , OPTION PACKAGE
24E TRIM COMBINATION , "CLOTH, DK BLUE (E) (91)"
24I INTERIOR TRIM , DK BLUE (I) (94)
47U PRIMARY COLOR , "EXTERIOR, DK BLUE MET (02)"
6CF COMPONENT FRT LH , COMPUTER SEL SUSP (6CF)
7CF COMPONENT FRT RH , COMPUTER SEL SUSP (7CF)



i just picked up a G80 diff today at a pick n pull i forgot to get the codes from the glove box no idea what ratio it is now... i probably will never see that blazer again... crap.

[03blazer]

My '03 says it has the GU6 and G80.

So I'm assuming that means 3.42 gears with the locker. Sounds good to me.

[What?]

http://www.c2e.info/rpocodes/gmrpocodesGthroughM.html

[Golana]

my new posi diff is a 4.11 locker =D

[Toadz]

I checked out the one site for RPO codes but it didn't have quite a few of what's in our Blazer's glove box. Is there an official site that has all the codes?

The codes I'm still trying to figure out are:

AXP, BQ2, BQ3, C3H, DAY, FLT, QBF, RYJ, TFD, VN9, VX5, XBF, YBF, YD5, ZQ6, ZW7, 1SZ, 6WH, 7WH.

[2002dime]

GT5 4.10's in my 02 manual trans, ext cab

[Toadz]

Quote: Originally Posted by 2002dime

GT5 4.10's in my 02 manual trans, ext cab

Same in my '96 ext cab. Wish it had enough power to push a 3.73 or 3.42 because I hate the high RPM's at 60 mph.

Has anyone found a site with ALL the RPO codes?

[Disturbed R.I.]

how about an 86 2wd s10 blazer 2.8l 5-speed? i dont have the truck anymore to check the code,can someone help me out with the gear ratio on this rear end?

[Disturbed R.I.]

well....from what i read here,the 2wd blazer 5 speed had the 3.42, so it would be better for me to run the 3.42 opposed to the 4.10s that my 94 2.2l automatic truck came with....correct?

[s104racing]

Can anybody tell me the correct way to check rear ratio w/o removing diff cover and my RPO is missing and I have another rolling chassis that Im putting a 1935 chevy sedan on top of. One Chassis is a 1985 w/ 2.8/5speed ext cab and the other is a 1987 w/ 2.8/5speed std cab long bed. Any help is appreciated

[MARS2878]

I'm Going To Take Out The G80 / Gt4 Rear W/drums Out Of My '93 Bravada & Put In The G80 / Gt4 Rear W/discs That Was In My '98 Bravada.

I Also Have Rpo's That Come Back Unknown.

[MadMeador]

Anyone....I have a 03 ZQ8 with drums...GU6,G80...I have an Zex. Torsen out of an 02 ss camaro...It should be the right carrier right?

[RickRock]

I don't know about finding out the gear ratio without taking off the cover, but I can tell you how to tell the ratio if you do take it off. It's very simple. You count the number of teeth on each gear and then divide the output by the input.

I had a question, though, I have a GU6, also, open diff. I'm going to go junk yard diving to find a G80 soon. Will it have the GU6 and G80 in the glove box? Cause my truck's 4wd and I don't want to fry my T-case by having different ratios up front and in the back.
Also, do all second gens fit on all second gens? My truck's a 96, will I be able to but a G80 from a 98-99 in mine?

[smoky86]

I have a 86 S-Dime and I just lost my rear end. I need to know the RPO code for a 4.11 rear end. I know that's what it has b/c it says so in the glove box.

[Golana]

ummmmm... the glovebox gives you the RPO... so if you see it in the glovebox... thats what it is...

[s-tung]

Quote: Originally Posted by s104racing

Can anybody tell me the correct way to check rear ratio w/o removing diff cover and my RPO is missing and I have another rolling chassis that Im putting a 1935 chevy sedan on top of. One Chassis is a 1985 w/ 2.8/5speed ext cab and the other is a 1987 w/ 2.8/5speed std cab long bed. Any help is appreciated

Good question. I'm wondering the same thing myself. If the glove box is part of a spongebob square pants lunch pail somewhere, and the S10 or Blazer has been melted down and turned into fence posts, how can you determine what gear ratio you have without taking the cover off? A junkyard prob isn't going to let you rip a cover off to see. So, did GM stop putting codes on the axle tubes? If not, where are they located and how do you decipher them? Simple question.

Anyone?

[smoky86]

Quote: Originally Posted by Golana

ummmmm... the glovebox gives you the RPO... so if you see it in the glovebox... thats what it is...

I'm needing a new rear end because the one with the 4.11's blew apart. Me acting like a goober. I need to know what the RPO code for a 4.11 rear end is, so I don't get the wrong rear end when I get around to fixin it.

[swamp_rat]

in my 91 it has GQ1 and GU6. from the codes its a 3.42, but whats the GQ1 there for? and is that a good ratio?

[chevyfan87]

so, my glove says i have a 3.08, but a previous post on here said that with the 4.3 that was only an option on the 5spd models....what is up with that?

[JeffG]

I found a 89 s10 4cyl 2wd 5spd, reg cab, The truck is 1.5hrs away and I am having a buddy look at it... What would be the norm. for gears in this truck??

[smoky86]

I think I know the RPO code for my truck now. I just want to make sure before I go and buy a new rear end for my truck. on one side of the chart in my glove box it says 6HO4 and directly over in the next column it says rear end 4.11 ratio. Any help would be appreciated.

[swamp_rat]

are all 10bolt rear gears the same as far as swapping them from a full size to a s10 or no?

[drperry]

Quote: Originally Posted by Jr's z

does anyone have a 4.3 5 spd w/ 3.42's or 3.73's.. hows the gas milage, and the revs at 100kms/60mph?

Can't remember the RPM at those speeds since I have 30" tires on my 3.42s, but with factory rubber on my 4x4 Blazer, got 24 MPG @ 120km/h.
That's a 5-speed, btw.

Quote: Originally Posted by swamp_rat

are all 10bolt rear gears the same as far as swapping them from a full size to a s10 or no?

Not gonna work... A full size axle is way too wide to fit there.

Best place get the 8.5" rear is from a 5-speed V6.
The ZR2 axle is probably too wide for a 2WD. (However is a GREAT way to get the front/rear to be pretty much the same width on a 4x4!)

GU6 and G80 for me...

For people swapping gears, remember that 3.08s and 3.42s are on different series carriers... Series 2 for the 3.08s and lower (2.73s for instance) and possibly 3.23s as well... 3.42s and higher are on a series 3 carrier.

[sublevel]

Quote: Originally Posted by s-tung

Good question. I'm wondering the same thing myself. If the glove box is part of a spongebob square pants lunch pail somewhere, and the S10 or Blazer has been melted down and turned into fence posts, how can you determine what gear ratio you have without taking the cover off? A junkyard prob isn't going to let you rip a cover off to see. So, did GM stop putting codes on the axle tubes? If not, where are they located and how do you decipher them? Simple question.

Anyone?

This is a good question, I just bought a rear end form a junk yard and was told it was a 4.10 rear, I found the "10:41" on the ring gear to confirm it was a 4.10 ratio, in my 1994 FSM it talks about the axle codes on the right axle tube, but I haven't seen the letters/number on either rear end... I have a vin that was supposed to go with the rear end I bought and it checks out to be a 1995 2.2 with 4.10 but the yards item/stock number didn't match up to the rear end - so I have no way of knowing the detail of where it came from

if anyone has pictures of where to look for the stamped axle code it would be nice to see

[orangesonoma]

spin the axle shaft and count how many times it turns and count when the pinion rotates one time...

so if it pinion yoke thing spins one full turn and you spin around your axle 4.10 times...then you got 4.10's

[Ruthless]

mine has gu6 and gq1 right next to each other... can someone explain?

2.5 manual.

well.. was!

[drperry]

GQ1 I'm fairly certain is the RPO code for the 7 5/8" diff.

[crazy_s_dime]

i love my 94 4.3L with 5spd and 2.73. i get 23-24 on highway w/ A.C. and the engine sits about 2100 rpm

[drperry]

2.73? or 3.73?

Last highway trip I took, I got 18MPG @ 75MPH with a/c and my 30x9.5" BFG A/T's which are 7lbs heavier than factory rubber, lol.

[The Stunningman]

Quote: Originally Posted by orangesonoma

spin the axle shaft and count how many times it turns and count when the pinion rotates one time...

so if it pinion yoke thing spins one full turn and you spin around your axle 4.10 times...then you got 4.10's

You got that backwards. Easy to get that confused. The pinion will turn 4.1 turns to the Axle/Wheel turning once. That also doesn't work well on open differentials because the spyder gears come into play. The other wheel needs to be turning at the same rate.

[crazy_s_dime]

Quote: Originally Posted by drperry

2.73? or 3.73?

Last highway trip I took, I got 18MPG @ 75MPH with a/c and my 30x9.5" BFG A/T's which are 7lbs heavier than factory rubber, lol.

yes, you read it right, some of the early 2nd gens like mine have the 2.73 rearend. It even states that on the original window sticker in my glovebox. 2.73 mated up with the long gears of the NV3500 makes for some good highway mileage. i even have TBI injection too, and I still get 23-24 with A/C on

[PimpingA1997Jimmy]

so this will be on a sticker in the glove box ?

[greencactus3]

Quote: Originally Posted by The Stunningman

You got that backwards. Easy to get that confused. The pinion will turn 4.1 turns to the Axle/Wheel turning once. That also doesn't work well on open differentials because the spyder gears come into play. The other wheel needs to be turning at the same rate.

well hold one wheel still, then youd get 4.1 turns at the pinion to 2 turns at the non stopped wheel

[vjcustoms]

hey quick question!!!

i have an 82, but there is no stickers in my glove box...i know its all original, when did they start putting rpo stickers in the glovebox?

oh, and i found a gu4 g80 at the yard today, 75 bucks, i just dont feel like taking it out of the blazer. ill just go buy a real posi.

[Hoop]

Quote: Originally Posted by DoubleDown

GU4=3.08
GU5=3.23
GU6=3.42
GT4=3.73
GT5=4.10
HC4=4.56

G80 - locking differential


compare to the codes in your glove box to know which gear ratio you have

How good is a GT4=3.73

[drperry]

Quote: Originally Posted by crazy_s_dime

yes, you read it right, some of the early 2nd gens like mine have the 2.73 rearend. It even states that on the original window sticker in my glovebox. 2.73 mated up with the long gears of the NV3500 makes for some good highway mileage. i even have TBI injection too, and I still get 23-24 with A/C on

Nice!

That kind of mileage and those gears is only going to happen on the S10/Sonoma, though... The Blazer is too heavy for it
My 2 door weighs in at 4200lbs.

Quote: Originally Posted by Hoop

How good is a GT4=3.73

Depends on what you're looking for... You'll get a little more acceleration out of that, and a little less top speed...

[MikeInCtown]

Since the stickers just have the codes all listed one after the other in rows and columns, how does one know where on the sticker to look? It's just a PIA sometimes trying to find a code for something when you have no idea where on the sticker you need to look or what the numbers could be.

[drperry]

Should be in alphabetical order, if I remember right.

[98SS]

Heh .... I have probably 100 pages of this stuff. If I could ever find enough time to scan it all, I might.

Here's a couple pages with a ton of axle codes. (click)

[96S10]

Quote: Originally Posted by meangreen9c1

Don't all 2.2s come with the 4.10s?

They were also available with a 3.73.
My 96 2.2 had 4.10's thank goodness.

[drperry]

Hopefully only manuals came with the 3.73!

[AntFJ]

thought i'd share my find.. (unless I did it wrong).. both wheels off the ground.. spinning one wheel twice gave 3.7 turns of the driveshaft so...

for a 84 pick-up 4x4 2.8l 5speed i have a 3.73

at 65 in 5th I have 2000 rpm with 31' tires

PS anyone in the CT are have a spare axle.. my ring and pinion gear are busted..

[Golana]

using this script:

http://www.philter.com/cgi-bin/drac.pl

does anyone know how many pulses/rotation our trucks do? cause im using the default 40, and im using my axle code from the glovebox, and im using my tire size, and im not coming up with what my drac module has...

rear end: 3.36 (apparently)
tire size: 205/70r15

my stock tire DRAC settings are 1,3,5,6,7

i dont know what i punched in to get that though... pisses me off, cause i cant get it again. the speedometer is set perfectly, so im trying to figure out how to make it set for my new tires

tire size: 215/65r15



thanks all

[Golana]

Quote: Originally Posted by Golana

using this script:

http://www.philter.com/cgi-bin/drac.pl

does anyone know how many pulses/rotation our trucks do? cause im using the default 40, and im using my axle code from the glovebox, and im using my tire size, and im not coming up with what my drac module has...

rear end: 3.36 (apparently)
tire size: 205/70r15

my stock tire DRAC settings are 1,3,5,6,7

i dont know what i punched in to get that though... pisses me off, cause i cant get it again. the speedometer is set perfectly, so im trying to figure out how to make it set for my new tires

tire size: 215/65r15



thanks all

i looked up my RPO code from above, and its a 5.42 gear ratio... and it works... how could i have 5.42 gearing?

[drperry]

I wonder if it's a typo...

I don't know if a 5.42 setup can fit in there... And be durable, at least, lol.

[Golana]

Quote: Originally Posted by drperry

I wonder if it's a typo...

I don't know if a 5.42 setup can fit in there... And be durable, at least, lol.

i dunno... i plugged the 5.42 numbers into the DRAC calculator so i could calibrate my speedometer, and it reads correct now... ODD!!!

there is no way i can have a 5.42 gearset and get 26mpg with a 4.3L... its just not possible...

[skater35k]

im swapping my motor out of my 95 simply because the body and frame is shot to hell. im going to put it into a 1st gen truck and wanting the best gas mileage possible. i was looking into getting the 3:08 gears but im not sure if it will excelerate to slow. what do you guys think

[drperry]

If it's a 2wd it'll be livable.

[skater35k]

yeah its a 2wd. its the 2.2 4cyl motor. how much difference will it make? should i maybe go with the 3.28 or even 3.42