Rear Diff 3.73 Or 4.10

cm5 · November 15, 2007

hi, some quick questions about my 2007 vmax gmt 900...

when i bought the truck i could have sworn it came with the max trailering package. it does have the tranny cooler, vmax engine, z85 suspension package and i assumed it had 4.10 gear ratio. i looked quickly at the pumpkin and its a 14 bolt 10.5.

i decided to look in the glove compartment and it has RPO code GT4 which indicates 3.73.

i looked under the truck and on the axel itself it has the following code

ZR9 G008 0720

L 300506

does anyone know how to decipher this code?

also not saying i will, but if i wanted to swap the 3.73 for 4.10 (i do occasional towing and dont care about gas mileage as its not a daily driver) would it be expensive?

i wont lie...i like the idea of 4.10 for the power.

any prefences to the 4.10 over the 3.73?

p.s. wanted to introduce myself...im 28 living in MA (south shore) and i been meaning to post pics of my trucks.. not even sure how to do it! i have owned a 1988 silverado (trim!) 3500 reg cab (traded), 2001 silverado 1500 ext cab (traded), 2005 reg cab silverado (totalled) and currently own a 2006 reg cab silverado and a 2007 vmax gmt900. i like toys and not a fan of cars...

my dad was a loyal chevy guy for years but dissapointed in his 1988 chevy and wne to dodge (he hated it) then currently to a 2002 f350 ford super duty. my older brother followed suit and owns a 2005 f1sh!tty. suffice to say holiday dinner tpoics are sometimes heated in my family!

i been reading this forum and just recently signed up. been leaning alot from all of you and have to say im addicated to this site. (when work allows me to contribute)

C & A s Dad · November 15, 2007

I cannot help you with your code but I will vote for the 4.10s. I have them in my Yuk XL and am really happy they are back there when towing my 6500lb camper. On the other hand, my Yuk XL is an 02 and does not have the HP that your truck has. I feel sure your HP and the 3.73s will be fine unless you plan to be towing in the very upper ranges of your max weight. Either with the 4.10s or 3.73s pulling in 3rd gear instead of OD will keep your motor right in it's "sweet spot". This really works for me as most of my towing is on two lane, 55mph roads. If you plan on pulling on the Intersates, you may can run OD and still be in your motors sweet spot.

MS3DALE · November 15, 2007

Is it 2wd? Also look in your glovebox for RPO code "NHT"

The 2wd's with the "NHT" package have 3.73's,The 4wd's with "NHT" have 4.10's.

Also,If you PM me your VIN and e-mail address I can send you a copy of your trucks build sheet.

cm5 · November 15, 2007

Is it 2wd? Also look in your glovebox for RPO code "NHT"
The 2wd's with the "NHT" package have 3.73's,The 4wd's with "NHT" have 4.10's.

MS3DALE -- its 4WD. i will have to check for NHT. thanks!

C & A s Dad -- yea im sure the 3.73's will be fine with what i tow and how often. thanks!

jrrod2004 · November 15, 2007

hi, some quick questions about my 2007 vmax gmt 900...

when i bought the truck i could have sworn it came with the max trailering package. it does have the tranny cooler, vmax engine, z85 suspension package and i assumed it had 4.10 gear ratio. i looked quickly at the pumpkin and its a 14 bolt 10.5.

i decided to look in the glove compartment and it has RPO code GT4 which indicates 3.73.

i looked under the truck and on the axel itself it has the following code

ZR9 G008 0720

L 300506

does anyone know how to decipher this code?

also not saying i will, but if i wanted to swap the 3.73 for 4.10 (i do occasional towing and dont care about gas mileage as its not a daily driver) would it be expensive?

i wont lie...i like the idea of 4.10 for the power.

any prefences to the 4.10 over the 3.73?

p.s. wanted to introduce myself...im 28 living in MA (south shore) and i been meaning to post pics of my trucks.. not even sure how to do it! i have owned a 1988 silverado (trim!) 3500 reg cab (traded), 2001 silverado 1500 ext cab (traded), 2005 reg cab silverado (totalled) and currently own a 2006 reg cab silverado and a 2007 vmax gmt900. i like toys and not a fan of cars...

my dad was a loyal chevy guy for years but dissapointed in his 1988 chevy and wne to dodge (he hated it) then currently to a 2002 f350 ford super duty. my older brother followed suit and owns a 2005 f1sh!tty. suffice to say holiday dinner tpoics are sometimes heated in my family!

i been reading this forum and just recently signed up. been leaning alot from all of you and have to say im addicated to this site. (when work allows me to contribute)

Welcome to the forum, if you do it yourself you will definitely need a new ring, pinion, and a new carrier (could be mistaken here though). It can be labor intensive, if you have the mechanical background, you should be able to do this swap. Did a quick price check, and depending on where you get the parts, you may be looking anywhere from $420.00 to $795.00 from online suppliers (Carrier, ring and pinion). I have not done a rear end swap, so I cant tell you exactly how much you would be spending for the whole job. Worst comes to worse and you dont want to mess with it, take it to a shop or dealership.

cm5 · November 15, 2007

yea i'm sure it will be a lil too intensive for me. prolly wont be ponying up that much cash for a sawp like that anytime soon. thanks!

ws6_guy · November 15, 2007

Welcome to the site. 4.10s are better for the low end power, hopefully you will already have them. Does the MSRP sheet say anything about the gears included in the optional equipment?

cm5 · November 15, 2007

Welcome to the site. 4.10s are better for the low end power, hopefully you will already have them. Does the MSRP sheet say anything about the gears included in the optional equipment?

i have the window sticker which does say 3.73, and the glove box has the code GT4 which im pretty sure indicates 3.73. so it prolly is...but i did email gmpartsdirect with my vin just to double check.

as i said before just seems odd that it has all the compents of the max trailering package except the rear gear ratio..

MS3DALE · November 15, 2007

as i said before just seems odd that it has all the compents of the max trailering package except the rear gear ratio..

No,Its really not odd,Because you can get the 6-liter engine WITHOUT getting the "NHT" Max Trailering Package.

Thats how my truck is...."VortecMAX" 6-liter,Super-Duty Trans,14-bolt 9 1/2" rear-end w/3.73 gears,and all the external coolers,Plus I have the "PCY/Z82" towing package.

Heres a post of mine from another thread explaining the details....

"On the '07 "GMT900" 1/2-ton trucks you can get the "VortecMax" 6-liter (RPO L76) two ways,Either as a seperate option on the crew-cabs and ext.cabs (short or standard length bed) or its comes as part of the "Max Trailering Package" (RPO NHT) available on crew-cabs and ext.cab (standard length bed only)

When you spec it out as a seperate option you get the "L76" 6-liter along with the "M70" 4L70E "Super-Duty" transmission and the 9.5" rear-end with 3.73 rear-end gears & HD cooling and you can still get the Z71 package or the Z60 suspension with 20" wheels.

When you spec out the "NHT" Max Trailering Pkg. it also comes with "L76" 6-liter,"M70" 4L70E transmission and the 9.5" rear-end & HD cooling,but it also includes the "G80" locking diff. w/4.10 gears in the 4x4 models (3.73 gears in 2wd models) it also comes with the autotrac transfer case on 4wd models,fog lamps,"Z82" trailering pkg.,"Z85" handling/trailering suspension,H.D. rear springs,bigger front sway bar,a "slotted" front bumper and Stabilitrak,This package increases towing capacity up to 10,500lbs. Also 17" wheels are the only wheel size available with the "NHT" Max Pkg.

You'll notice the biggest difference between the two is the fact that with the "NHT" pkg. it comes with 4.10 gears in 4wd models,this is where they get the 10,500lb. towing capacity,If you get the 6-liter as a seperate option you can only get 3.73 gears which is limited to an 8,500lb. towing capacity.

Also on the rear-end,If you get a crew-cab it will have rear disc brakes because stabilitrak is standard on all crew-cab models,however on ext-cab models drum brakes are std. unless you order the stabilitrak option seperately or the "NHT" pkg. which includes stabilitrak as part of the pkg."

Hopefully that wasn't too confusing!

jrrod2004 · November 15, 2007

now you know why I stick to the service side of DealerWorld, sales ordering bench is just too complicated.......

MS3DALE · November 15, 2007

now you know why I stick to the service side of DealerWorld, sales ordering bench is just too complicated.......

Ahh yea Mike,I deal with all three sides of DealerWorld....Parts,Service and Sales!

Unfortunately I have to keep the salesmen straight on everything here.

My brain is fried at the end of the day

GM Dude · November 15, 2007

hi, some quick questions about my 2007 vmax gmt 900...

when i bought the truck i could have sworn it came with the max trailering package. it does have the tranny cooler, vmax engine, z85 suspension package and i assumed it had 4.10 gear ratio. i looked quickly at the pumpkin and its a 14 bolt 10.5.

i decided to look in the glove compartment and it has RPO code GT4 which indicates 3.73.

i looked under the truck and on the axel itself it has the following code

ZR9 G008 0720

L 300506

does anyone know how to decipher this code?

also not saying i will, but if i wanted to swap the 3.73 for 4.10 (i do occasional towing and dont care about gas mileage as its not a daily driver) would it be expensive?

i wont lie...i like the idea of 4.10 for the power.

any prefences to the 4.10 over the 3.73?

p.s. wanted to introduce myself...im 28 living in MA (south shore) and i been meaning to post pics of my trucks.. not even sure how to do it! i have owned a 1988 silverado (trim!) 3500 reg cab (traded), 2001 silverado 1500 ext cab (traded), 2005 reg cab silverado (totalled) and currently own a 2006 reg cab silverado and a 2007 vmax gmt900. i like toys and not a fan of cars...

my dad was a loyal chevy guy for years but dissapointed in his 1988 chevy and wne to dodge (he hated it) then currently to a 2002 f350 ford super duty. my older brother followed suit and owns a 2005 f1sh!tty. suffice to say holiday dinner tpoics are sometimes heated in my family!

i been reading this forum and just recently signed up. been leaning alot from all of you and have to say im addicated to this site. (when work allows me to contribute)

Best I can remember is the 4.10's are only available with 4WD option & 3.73 are the lowest you can go on the 2WD...

Oops, should have read on, I see it is 4WD, also remember that since it is 4WD you have to do both front and rear axles if you decide to swap out to 4.10's so double the price that was quoted earlier. I did my 05 2WD Sierra going from 3.23 to 3.73 and best I remember it cost around $600.00 including new PCM from Wait4Me programmed for the gear change as well as the 20" tires and a lot of TM removed.

Good Luck