# 3.73 vs 4.10?



## Kollerman (Jan 2, 2008)

Hey Guys,

I found a 2005 GMC 2500HD at a local dealership. It has the 6.0L engine with about 41,000 miles on it and the thing is mint! Very clean and the previous owner took excellent care of it. It has a 8.2 Boss V on it as well. The previous owner put it on to do a small apartment complex that he lives in so that he could get a break on rent. 

Here is my question. The dealership said the truck has the 4.10 rear end in it. I am wondering how much difference in gas mileage there is between the 4.10 and 3.73 rear ends? I know you that everyone is probably going to say that if you are worried about gas mileage, don't buy a 3/4 ton. But this would also be my daily driver and I drive about 40 miles round trip each day, so gas mileage is kinda important to me. I would like to get a 3/4 ton not just for plowing, but also because I also have a 25ft camper that I pull around pretty much all summer long. My family and I go to different parts of the state camping and I think the 3/4 ton would handle the camper much better and last longer.

I currently have a 2000 GMC 1500 and I don't mind the gas mileage at all. I get about 18-19 on the highway and about 14-15 in the city. If I would go after this truck, am I going to see a drastic decrease or not?

Jeremy


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## mkwl (Jan 21, 2005)

That truck will have the 4.10's for sure- GREAT for power and torque- not good for fuel mileage. I see around 8-9MPG around town, 10 if I'm lucky, and around 12.5-13 Highway.

Best of luck with the purchase!


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## ChevKid03 (Dec 23, 2007)

Yea, you'll see a drastic decrease... I had an 03 with the 6.0 and 4:10's... Lets just say you drive to work 40 miles round trip... figure about 11-12 mpg if your going easy... The tank holds 26 gallons.... Just driving to work and not going ANYWHERE else, you'll be filling the tank every week and a half.... You'll be putting roughly $70 a fillup.... If you can swing it... do it.. I loved that truck but wanted the diesel. That's why I sold it.


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## Novadiecast (Jul 16, 2007)

My 07 Classic CCSB with a Boss V gets 11.5 with no plow, about 9.5 with plow on, and 4.5 plowing as per the computer.


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## B&B (Nov 4, 2006)

If you're plowing during the winter and towing all summer long you want the 4.10's with the 6.0 regardless.


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## papa (Dec 12, 2007)

I have a 2001 2500 with the 6.0 and 3.73's.

on the highway empty I get about 15.

around town 11-12

pulling my 7x14' box trailer loaded about 8-10


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## Chrisxl64 (Dec 10, 2008)

if its a matter of 1-2 miles per gallon difference and you intend to work the truck,,,go with the 4.10's your better off. If youre getting killed on gas as it is,,,mind as well get top performance out of it,,,even if it costs you 1 or 2 mpg.


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## Motorman 007 (Jan 11, 2005)

B&B;994315 said:


> If you're plowing during the winter and towing all summer long you want the 4.10's with the 6.0 regardless.


Yeah, what he said!!!


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## mayhem (Aug 25, 2006)

I have a 2000 2500 6.0, 4.10 extended cab. I get about 12 city, 13 or so highway. You'll find it launches alot more easily and you can get a hevay load moving with alot less work witht eh 4.10's. The kicker is you pay for it with highway economy. If they put a 5sp auto in them, this would be moot.

I agree with B&B though, it sounds like you use your truck as a truck really frequently and you'll be alot better off in the long run with the taller gears.


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## Scott13136 (Dec 25, 2008)

I can not speak for the 6L but, we have 2 6.6L with 3.73 and 1 with 4.10 and I get the same mileage with all 3. The other 2 drivers get better milage than I do. Can we say driving style?


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## JustinD (Jan 14, 2008)

Scott13136;994521 said:


> I can not speak for the 6L but, we have 2 6.6L with 3.73 and 1 with 4.10 and I get the same mileage with all 3. The other 2 drivers get better milage than I do. Can we say driving style?


A Duramax with 4:10's? I wasn't aware that option was available???


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## Scott13136 (Dec 25, 2008)

it is an 03 3500 CCdually


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## JustinD (Jan 14, 2008)

Pretty certain all Duramax equipped pick up trucks got 3:73's only ones that got 4:10's were the 4500 and 5500 trucks.


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## 1500hdcntryboy (Jan 4, 2010)

1500HD's have an option for the 4.10's and the 2500HD gassers and diesels come standard with the 4.10's


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## Scott13136 (Dec 25, 2008)

I cannot "prove" that the 03 has 4:10s in it. I went over last night to see if there was any documentation on it, and there was none. I will see if I can locate the window sticker from the origional purchase, it might still be on record some place.

If it does not have 4:10 then that woudl explain my getting the same milage on both. I did how ever confirm that when the truck was purchased he was* told* that it had 4:10 because it had the trailer package and it was the largest p/u available without going to the 4500.


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## 1500hdcntryboy (Jan 4, 2010)

look for the rpo code in your glove box, GT4 is the 3.73 gear and GT5 is 4.10, G80 means you have the locking differential


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## Scott13136 (Dec 25, 2008)

all three have 3.73s thank you for the information.


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## ontario026 (Dec 22, 2008)

papa;994323 said:


> I have a 2001 2500 with the 6.0 and 3.73's.
> 
> on the highway empty I get about 15.
> 
> ...


must be nice, my 2000 6.0 ECSB 3.73 unloaded, I think the absolute best I have ever gotten was about 11.7MPG and normally average about 8.1-9.5 mpg....

Plowing is normally about 4-5mpg
Matthew


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## SawHoss (Feb 18, 2009)

My 2000 2500 (non HD) has the 6.0 with 3.73 gears, on the highway, ive seen as high as 17 (not going over 70 though) Usually, cruising at 75, i can just barely squeak out 16.5. In the city, im around 11-12 no matter what my driving style is. With my 2006 Duramax, cruising at 75, i can get 22 all day. Its a night and day difference. Also, while plowing, my duramax will get almost twice the mileage compared to my 6.0.


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## ontario026 (Dec 22, 2008)

SawHoss;999095 said:


> My 2000 2500 (non HD) has the 6.0 with 3.73 gears, on the highway, ive seen as high as 17 (not going over 70 though) Usually, cruising at 75, i can just barely squeak out 16.5. In the city, im around 11-12 no matter what my driving style is. With my 2006 Duramax, cruising at 75, i can get 22 all day. Its a night and day difference. Also, while plowing, my duramax will get almost twice the mileage compared to my 6.0.


Sawhoss, your truck sounds almost identical to mine, 2000 2500 non hd 6.0 3.73, but yours seems to smoke mine milage wise... I wonder why the big difference?
absolute best I have ever gotten was just shy of 300 miles to the tank (26gallons I think) especially in the winter my normal average is probably about 240 miles to the tank...

Matthew


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## tuney443 (Jun 25, 2006)

1500hdcntryboy;995014 said:


> 1500HD's have an option for the 4.10's and the 2500HD gassers and diesels come standard with the 4.10's


2500's and 3500's with the Dmax only come with a 3.73 axle.There was never a 4.10 even available from 2001-2010.Next year's model,GM is saying it will be available.As previously said, you could get a 4.10 in 4500's and 5500's.

''With my 2006 Duramax, cruising at 75, i can get 22 all day. Its a night and day difference. Also, while plowing, my duramax will get almost twice the mileage compared to my 6.0. ''

How are you getting this kind of mileage.Are you calculating it from your DIC or hand calculating? If you're running a much taller tire than the original 245-75-16,did you factor that in for the adjustment?I have a LBZ also--I hardly ever go 75--the trick is to keep the R's as far under 2K as possible.At 65. at app.1600 RPM,the best I've ever gotten was 16 MPG.My 3500SRW is completely stock,running original 265-75-16's.Plowing though this Winter with my Dmax for the first time vs.always using gassers[last 10 years with an old style,1988 SFA V30 dump]has been fantastic on fuel.I went from app.$130 in gas to about $30-$40 in diesel for my 8 hr. route.


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## SawHoss (Feb 18, 2009)

I hand calculate all of my mileage. Cant trust the dash mileage readout as far as you can throw it. With my 6.0, the only mods (if you can call them that) are an after market exhuast and a throttle body spacer (nothing that will really make a difference) Even before I did these mods, I have always been seeing this kind of mileage. I did go up one tire size (to 265) but I had the speedo recalibrated. (I did this on both trucks) The only other thing I do is run lucas oil fuel injector cleaner in both trucks on long trips up north (250 miles one way) Other than that, I drive pretty normal, the occasional pedal to the metal to pass someone, but thats about it.


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## tuney443 (Jun 25, 2006)

SawHoss;1000035 said:


> I hand calculate all of my mileage. Cant trust the dash mileage readout as far as you can throw it. With my 6.0, the only mods (if you can call them that) are an after market exhuast and a throttle body spacer (nothing that will really make a difference) Even before I did these mods, I have always been seeing this kind of mileage. I did go up one tire size (to 265) but I had the speedo recalibrated. (I did this on both trucks) The only other thing I do is run lucas oil fuel injector cleaner in both trucks on long trips up north (250 miles one way) Other than that, I drive pretty normal, the occasional pedal to the metal to pass someone, but thats about it.


I was just referring to your Dmax.There have been reports cited of up to 22 MPG over at the Diesel Place{I'm a member there too],but it's not the norm.Some guys were complaining they only got a hiway best of 14 empty.I really have to behave to get my 16.Maybe going to get a programmer when my economy gets better.


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## SawHoss (Feb 18, 2009)

From what I know, the best thing to do to a diesel to get better mileage is getting an exhuast. You can either get a full exhaust system, or the simple way, you could get a muffler or cat delete. By doing this, you get better flow with less back pressure (stock turbo gives you all the back pressure you need) and it should increase your mileage by about 1 mile per gallon. Using a programmer may void the warranty, and still not sure about how good it is at increasing mileage.


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## Kris_Kris (Feb 7, 2010)

If you end up putting a little larger tire on you will want the 4:10. I went up 1 tire sizes and the speedometer now agrees with my GPS. You are actually getting worse gas milage than you think if you are running the stock size.


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## Kris_Kris (Feb 7, 2010)

tuney443;999925 said:


> 2500's and 3500's with the Dmax only come with a 3.73 axle.There was never a 4.10 even available from 2001-2010.Next year's model,GM is saying it will be available.As previously said, you could get a 4.10 in 4500's and 5500's.
> 
> ''With my 2006 Duramax, cruising at 75, i can get 22 all day. Its a night and day difference. Also, while plowing, my duramax will get almost twice the mileage compared to my 6.0. ''
> 
> How are you getting this kind of mileage.Are you calculating it from your DIC or hand calculating? If you're running a much taller tire than the original 245-75-16,did you factor that in for the adjustment?I have a LBZ also--I hardly ever go 75--the trick is to keep the R's as far under 2K as possible.At 65. at app.1600 RPM,the best I've ever gotten was 16 MPG.My 3500SRW is completely stock,running original 265-75-16's.Plowing though this Winter with my Dmax for the first time vs.always using gassers[last 10 years with an old style,1988 SFA V30 dump]has been fantastic on fuel.I went from app.$130 in gas to about $30-$40 in diesel for my 8 hr. route.


You should let GM look at your truck if you can get 22 mpg at 75 mph all day long. I bet they would like to see it. Pretty much every one reports in at 18 or 19 mpg and that is taking it easy. 12 or 13 MPG when pulling a trailer. When I babied my dodge with the ac off and pulled out all of the tricks to try and get the best mpg that I could, I only got 18 or 19. You must have a pretty special truck.


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