Rear End Ratio RPO Codes Here

[N0DIH]

G80's in cars are clutch/cone type, G80's in trucks (at least 1988-up) are locking open diffs. The G86 in trucks = G80's in cars.

My 96 Burb had a G80 from the factory but someone replaced it with a G86 (Eaton Clutch) and I honestly loved it.

If you are the hot rod type on the street clutch or cone type posi's are actually faster accelerating when coming out of corners. Why? The lockers will unlock, but the clutch/cone types will keep trying to force the power into the wheels equally, so the inside tire coming out of a corner actually will do most of the work accelerating the truck, resulting in faster acceleration due to the inside tire needing to turn less revs to go around the corner than outside.

I can saw on my 94 Fleetwood Brougham LT1 going from 3.42's open to 3.08's posi was a nice improvement coming out of corners.

But you don't wanna be using the clutch/cone type for serious off roading.

[77 bonanza]

I have a 77 K10 the sticker is still in the glove box, but no codes for gears. theris a tag on the front diff, but is confusing to me it reads just like this 43 with 2 numbers over the other 2. would this denote a
3 0
4.33 ratio.

on the rear all I can find are a GM82 with an N under it and the #3896839. The rear is a 12 bolt I believe is a 8.875. I have a lot of slop in the rear end and may need new gears. any help greatly appreciated
thanks'
chris

[8716valver]

Love this thread

[92 Burban]

My 92 burban says GQ1 / Gu6 so what do I have? Both?
Or do I have GQ1 for the front & Gu6 in the rear?
What is "STD" for ratio on the GQ1?
10 bolt / 4x4 by the way.

[88Vic]

Unless someone swapped the gears it'll have the same ratio for the front and rear.

[92 Burban]

So would it be the STD or the 3.42?
Still dont know what STD is.

[jake2332]

mine are getting swapped tomorrow. Going from a 3.23 to a 3.73. I'll let you know what I think. I'm driving a 4.8L GMC Crew 2wd.

[Rail-Runner]

GM says the limited slip needs a factory additive when changeing the diff fluid,used it in my 94 and always locks up when needed.

[N0DIH]

Unless you have RPO G86 you don't have limited slip, you have open or if you have RPO G80, you have a locker, which does not need the diff additive.

Originally Posted by Rail-Runner

GM says the limited slip needs a factory additive when changeing the diff fluid,used it in my 94 and always locks up when needed.

[chevy4x494]

my 2003 has a g80 with 3.73's, i was wondering if these newer trucks came with 3.42's? My old 94 had 3.42's. I think the lower gear in this new truck is hurting my highway mpg's.

[camel66]

What if you don't have the original glovebox? I have numbers from the passenger side axle which is an ID# for it. Not sure how I can cross refrence to find the ratio of the axle?

[N0DIH]

Stop by local GM dealer, they can look it up with the VIN.

[Badass69]

Originally Posted by N0DIH

G80's in cars are clutch/cone type, G80's in trucks (at least 1988-up) are locking open diffs. The G86 in trucks = G80's in cars.

My 96 Burb had a G80 from the factory but someone replaced it with a G86 (Eaton Clutch) and I honestly loved it.

If you are the hot rod type on the street clutch or cone type posi's are actually faster accelerating when coming out of corners. Why? The lockers will unlock, but the clutch/cone types will keep trying to force the power into the wheels equally, so the inside tire coming out of a corner actually will do most of the work accelerating the truck, resulting in faster acceleration due to the inside tire needing to turn less revs to go around the corner than outside.

I can saw on my 94 Fleetwood Brougham LT1 going from 3.42's open to 3.08's posi was a nice improvement coming out of corners.

But you don't wanna be using the clutch/cone type for serious off roading.

The Gov Bomb has been around since 1973 in Gm trucks. It basically is still that exact same design and fails in the same manner it always has. They wanted to make a dummy proof locker that any Joe Blow could drive with. It works half @$$ anyways. The 9.5" and larger Gov locks don't seem to blow up like the ones in the 10 bolts.

For most anyones daily driver a clutch pack or cone gear limited slip would suffice. If you want to be a little more hardcore..... buy a real locker.

True lockers will get you througn a corner quickly as well. Take the original Detroit locker setup. It ratchets in corners, thus unlocking, when under a no power condition. Take that locker and hammer the throttle part way through the corner. It will lock back up and swing the rear of the vehicle around much like a tight limited slip will.

I personally like both styles...... minus the Gov lock. Since it is now looking like I am buying a new GM truck again....... I will probably have to do a swap. The package I am getting( Sierra All Terrain) has a Gov lock standard in the trucks 9.5" 14 bolt so I will probably replace it in a timely manner. Maybe even throw in a true Detroit Locker.... would be fun. Especially with the 6.2 it has in front of it......

[hookem27]

hey im doing a solid axle swap on my 01 silverado ext cab z71. and the front dana 44 has 4.09 gears and im wondering if i put 4.10s in the rear 14 bolt would that do damage to my truck?? thanks

[N0DIH]

Call Randy's Ring and Pinion. I am pretty sure that much "error" is acceptable.

There is a certain % that is ok. There has to be for tire wear. It is a %, so at say 2.56, 2.55, might not be allowed, but at 4.10, a 4.09 or a 4.11 I think is. It is a %....

[DeanDalton]

Guys,

I have a 1993 GMC two-door, 4x4 Yukon and I love the truck! But it has a teeny, tiny 10 bolt rear, 3.42 gears. I have a donor 1992 Chevy ECSB half-ton 4x4 with a 14 bolt, 3.73 gears.

This should be a simple swap as far as the basic dimensions between leaf springs and shocks, right? Just unbolt and switch, right?

But what about the universal joints? Are they the same? Will I need a special universal joint due to different drive shafts? The Yukon has a shorter drive shaft than the ECSB. Has anybody done the swap and encountered any difficulties.

My donor has RPO code GT4, G80. So what does DUP 5x1 mean. Several people have asked this question, but nobody has answered directly.

Also, is there any special web sites devoted to the two-door Yukons and Tahoes? Some parts for these trucks are specific only to the two-door models and can be very difficult to find.

Dean

[jonny4554]

I was wondering i looked in my glove box and found that mine is GU4. Would that make sense for 1997 GMC 2wd reg cab short box?

[97longbox262]

Originally Posted by jonny4554

I was wondering i looked in my glove box and found that mine is GU4. Would that make sense for 1997 GMC 2wd reg cab short box?

that's what i've got in my 97 2wd longbox 4.3 v6,


so according to my dad's sticker he's got the GT5 and the G80 so hes got 4.10's and the posi? its a 07 4.8 v8 4x4 ECSB

[evilnissan]

1993 K1500 Reg cab and long bed, 5.7, GT4 3.73 with G80(lsd).

Thanks for code list, I thought this truck felt like it had a LSD in it but I have not been in snow or mud yet to really tell and I still drive it like a old man do to it sitting for so long.

[nick613]

just took a look in my glove box... codes list was reallllly rough looked kinda like hyroglyphics (however u spell that) I saw KC4 is it possible that I mistook that for HC4? (4.56) Truck is a 93 K1500