How to tell if my Z66 has a locker

[MF Fly]

Hello
New member here. Welcome to my life.
I recently bought a 04 Z66 or at least that's what the decal says.
But after reading some posts I'm not so sure it's a true Z66. It has 17" wheels, the decal, rubber mats but all of those don't prove anything. It DOES NOT have rear load leveling shocks. The shocks on the rear are the same diameter as the fronts. But they could have been charged. Z66 is an optional package so it won't show on the vin. My last and only hope is a locker. So how does one tell if it has a locking differential without taking off the cover? Or driving in mud or sand. Snow and ice is out of the question cause I live in Virginia Beach. I am not a mechanic so please keep the answers to a layman's level. Thanks Mark

 

[EXT4ME]

Look in your glove box for the list of RPO codes for your truck.

Look for G80.

That is the G80 AXLE, REAR, POSITRACTION, LIMITED SLIP.

 

[EXT4ME]

Also, have a look at this forum section for the RPO codes and what they mean.

 

[ygmn]

Look on this same glove box label for Z66 code as well.

 

[redheadedrod]

Z66 is just a package code. You are more likely to have 2wd with the Z66 package. Initially I thought that was what it meant. The Z71 package relates to tires it came with and changes to the suspension, definetly 4x4 and has additional shielding intended for "off road".

 

[MF Fly]

Also, have a look at this forum section for the RPO codes and what they mean.

Hi.
Thank you guys for the quik responce. Since I posted I have learned a lot about RPOs. But for some reason, every time a question is answered it initiates more questions. The tag in the glove box is very informative. Mine has Z66. and I maneged to figure out that I do indeeed have Nivomate rear sef-leveling shocks. (RPO ZW7) Another indication it is a true Z66. So we got the "is it a real Z66" question answered. Now the meat.
RPO G80 is on my glove box list. But when I look up the definition of G80 it states: "Not Open Diff - Positraction / Limited Slip / Typ. Gov-Lock."
I'm not certain I know what all that means but what I am certain of is positraction and limited slip or different names for the same differential, neither of which is a locker. Positraction and automatic locking differentials are, from what I understand, two different beasts. So like I said, one question answered in a rather vague way just produces more questions. Or am I over thinking this? Something I am notourious for doing. Now "Typ Gov-Lock" could indeed be some kind of abbrevition for a locker since automatic lockers "LOCK" by way of a governer "GOV" inside the differential that locks when one wheel spins faster then the other. Does this mean I have a locker?

 

[EXT4ME]

The G80 has a centrifugal hardware locking mechanism that locks both rear axles together under certain circumstances, such as when the rear wheels spin while losing traction on loose surfaces, such as mud or snow.

Difference Between Limited Slip Differentials

 

[ygmn]

YEs up to 20mph... and differenc in rear tire speed above 20 mph does NOT activate the locker.

Sometimes the locker will stay engage if say you are driving offroad slow and stop...

TO disengage you drive in a reverse a bit it should unlock with a clunk.

I have had my truck for 19 years and I have a 2001 Z66 and can say I had it lock only once when I tried to make it lock by spinning tires in extreme wet lawn... and when it locks.... it will/can hit hard and sound really bad as a loud bang... depending on wheel speed.

 

[MF Fly]

YEs up to 20mph... and differenc in rear tire speed above 20 mph does NOT activate the locker.

Sometimes the locker will stay engage if say you are driving offroad slow and stop...

TO disengage you drive in a reverse a bit it should unlock with a clunk.

I have had my truck for 19 years and I have a 2001 Z66 and can say I had it lock only once when I tried to make it lock by spinning tires in extreme wet lawn... and when it locks.... it will/can hit hard and sound really bad as a loud bang... depending on wheel speed.

OK then. Well you guys are awesome. Thank you very much. And YGMN. Since you also have a Z66, which are the best replacement front shocks for the Zw7 suspension? I'm looking at Monroe Reflex but I reas reveiws that some reflex models are not suited for Zw7 front shock replacement. Mine OE shocks are leaking. I'm also looking at Bilstein B6 4600 series part number 24-065009 but the reveiws are mixed mostly saying they are stiff. Good for planting the tires on the road, good stability, less roll but you can feel every crack in the road so not so premium smooth. Any suggestions? I really need to get this right b4 I go to the mechanic at Treadquarters who told me my Nivomate rears were NOT self leveling shocks and were ordinary shocks. Lost loads of trust after that.

 

[ygmn]

I still have stock I think...

But I would go OEM since it was a premium ride suspension

 

[EXT4ME]

OK then. Well you guys are awesome. Thank you very much. And YGMN. Since you also have a Z66, which are the best replacement front shocks for the Zw7 suspension? I'm looking at Monroe Reflex but I reas reveiws that some reflex models are not suited for Zw7 front shock replacement. Mine OE shocks are leaking. I'm also looking at Bilstein B6 4600 series part number 24-065009 but the reveiws are mixed mostly saying they are stiff. Good for planting the tires on the road, good stability, less roll but you can feel every crack in the road so not so premium smooth. Any suggestions? I really need to get this right b4 I go to the mechanic at Treadquarters who told me my Nivomate rears were NOT self leveling shocks and were ordinary shocks. Lost loads of trust after that.

NIVOMAT are self leveling shocks.

Have a look at rockauto.com and see all of the shocks they have listed for your application.

Rockauto.com

I have a 2003 Z-66.

The previous owner had just installed a new set of Monroe 911505 Reflex Monotube Shock Absorbers on the front and Monroe 40210 Specialty Shock Absorbers on the rear of my 2003 Z-66 a few hundred miles before I bought the truck used.

Thank goodness, because those rear self leveling shocks are a bit pricey.

So far, I could not be happier.

 

[MF Fly]

NIVOMAT are self leveling shocks.

Have a look at rockauto.com and see all of the shocks they have listed for your application.

Rockauto.com

I have a 2003 Z-66.

The previous owner had just installed a new set of Monroe 911505 Reflex Monotube Shock Absorbers on the front and Monroe 40210 Specialty Shock Absorbers on the rear of my 2003 Z-66 a few hundred miles before I bought the truck used.

Thank goodness, because those rear self leveling shocks are a bit pricey.

So far, I could not be happier.

Ok good. Cause I was about to flip a coin. Heads Reflex. Tails Blistein. My mechanic recomended Relax and your happy with them so that's good enough for me. And yes. The rear revelers are between 4 and 5 hundred EACH!!. But mine are still good. Again. Thank you guys lots!!

 

[MF Fly]

Actually. I posted in a different thread about the front shocks. A member named "Bain Man" came back to me with the GM front shocks for Z66 (rpo Zw7) part number 89038595 from GM Direct. At $85 EACH they are about $10 more the Bilstein and $25 more then Reflex in my area. But to be honest. Price doesn't matter to me as much as performance. Any body have any experience with these shocks?
Thanks!