Rear End Ratio RPO Codes Here

[crh428]

do a search for rpo decoder, there are a bunch out there

[RyPkr_99]

Originally posted by crh428
Mine does too, and i checked, it is a posi, not a locker

Mine has 2 columns of codes on the sticker in the glove box, next to the codes it also has the description. I have a 3.08 rear end ratio, I forget the code 4u or something. Then in the next column I have a something-or-another-g80 and the description for that is "locking differential".

To be honest I don't even know the difference between posi and a locker. I know what a locker is but I'm somewhat unclear as to what positraction is. If anyone could explain that that would be great. And if anyone could shed some more light as to whether I have a locker or posi that would also be helpful.

[crh428]

Maybe it is a locker, can't really trust info you find on the net, anyways. As for what a posi is, it basically uses clutch packs and springs instead of mechanically locking. It serves the same purpose, though. A locker is better, as posi's tend to wear out pretty quick

[Klortho]

Here's one for you. The sticker inside of my 1981 GMC 1-ton shows a rear end RPO of GQ1, but the build sheet for the truck shows GT5 which is a 4.10

[snoman]

Originally posted by SierraMan
u can get it with a 4.56 ratio factory?

Some 2wd duelie P/U could be order with 4.56's in the past. I am not sure if you still can.

[ocwave]

G80 is the RPO code for the factory locker, not posi

[JB]

Originally posted by Uranium-235
Excellent! I have the 3.73, L/S. It would be nice to know what all those codes mean.

cool, thats what I have in the 4x4 burb

[LW93Rcode]

Cool, I just look in my Tahoe and it has a GT4 and a G80, so I guess that means its a 3.73 Limited Slip. There was also a G65, does that anything to do with the rear also?

[LW93Rcode]

That's about how the traction-lok looked in my Lightning when it went. Now it has a nice Eaton with carbon fiber clutches, so far so good. At least with the Tahoe I'm starting with an Eaton. Maybe not as good as an aftermarket Eaton unit, but still tons better than a Ford Traction-lok.

Judging by the pic, you did it right

[addiction2bass]

whats the beter of the rear ends ratios?

my truck has a 305 with the GU6 -- AXLE REAR, 3.42 RATIO

i want more get up and go. so code should i look for at the junk yard?

and with swaping out the rear end would i have to replace the speed sensor? or do you think the junk yard would include that also?

and well with swaping out the gears does that change any torch/horse power/or top speed?

[LW93Rcode]

A lower gear (higher numerically) will give you a bit more grunt down low. Depending on your engine combo you may lose some top end, and you will raise the RPMs at cruising speeds a bit. HP and TQ don't change, just when its applied to the ground.

[addiction2bass]

well on regearing mine myself i have no clue where to buy those gears from! and wouldnt i need to change something in the trany or something so the speedometer works properly?

[moto12head]

what is the best gear ratio for my truck? ('94 Z71, reg cab, long bed, 4" susp lift, engine is bone stock, dual exhaust. i pull a trailor on occasion, otherwise i drive it about once a week around town. i go on several long trips a year.) stock 3.42's right now. any suggestions?

[popknot98]

any1 else have the 1SZ code?? it has ??? next to it, just curious, maybe my truck is the super duper space edition thats worth a gazillion dollars!!! get off my cloud damn it

[addiction2bass]

ive looked around at my local junk yards AND NO ONE HAS A 4.10 OR 3.73
LOOKS LIKE I CANNT SWAP EM OUT

how much a new rear end cost from the dealership at cost? im setup thru my dads company to buy direct preaty cheap but ive never asked the cost for a rear end.

[alwhite00]

I just put a Powertrax in it, Love it. 00 GMC ECSB 2wd & a 5.3 auto.

LK

[bigcfromcinci]

mines posi 3.73..i want 4.11's at least would like 4.56's

[addiction2bass]

Originally posted by bigcfromcinci
mines posi 3.73..i want 4.11's at least would like 4.56's

well if ya swap the rear ends ill buy your 3.73 :)

[CoolBlueSS]

Originally posted by kenyon
I can't seem to find the rear end code in my '01 tahoe. I see the big list of 3 digit codes in the glove box, but not one of them even start with a "G". Any help?

The first 2 letters in the code are either GT or GU. Codes are listed in alpha-numeric order, left to right.

Originally posted by 981500Chevy
I didnt know a rear end consisted of this many parts...

The old ones with the clutch packs and springs had a hell of alot more.

[itbrian]

Originally Posted by kenyon

I can't seem to find the rear end code in my '01 tahoe. I see the big list of 3 digit codes in the glove box, but not one of them even start with a "G". Any help?

If the codes are not list you can check it yourself by jacking up the back of the truck, chock the front wheels first. Then put it in neutral and mark the driveshaft and the tire. Have someone turn the tire one complete revolution while your counting how many revolutions the driveshaft makes.
If the driveshaft turned just over 4 complete turns it's a 4.10 if it turned
3 and 3/4 turns it's a 3.73 and so on.