2008 diesel questions

[DrHolliday]

I've decided to trade my 97 Sierra on a 2008 GMC 2500 diesel.

I love the gm trucks and want to go with GMC b/c I like the grills better than the chevy trucks.

What I want to know is can I get the truck with anything other than the 3.73 rear end? I'd like to get the best fuel mileage possible.

Also, I know some people have had problems with the particle filter and the truck getting poor mileage when it goes into regen mode. I know what its doing, but want to know if there is any tune out for them yet to stop the regen mode to let you take off the filter?

I plan to keep it stock for a while but would like to see what options i have.

Any other info on the truck would be appreciated as well. I can't wait till tax season to place my order!

Thanks for the info,
Doc

[98[GMC]z71]

are you talking about the "exhaust filter" when you say particle filter? If your talking about that...I know you can have it re-programed to disable the sensors without it going into the "limp" mode....

[justy]

So far I've seen most diesel with the 3.73 rear end and a few with 4.10. But I have not seen one with a 3.42 rear end. It's a truck for pulling not for fuel mileage. Truck is to heavy to be a economy car. If you wanted economy you should of waited for 2009 when the diesel half ton is on the road. I get with the 3500 around 18 mpg. But thats not really fuel economy. But still better then alot of gas hogs.

[ZsevneeONE]

get EFI live an turn your regineration crap off an get some exhaust an you will get decent fuel mileage an get everywhere pretty fast too.but being serious if your worried about fuel mileage a diesel might not be for you,sounds like you might be on a budget and budgets an $45,000 trucks usually don't work.

[DrHolliday]

get EFI live an turn your regineration crap off an get some exhaust an you will get decent fuel mileage an get everywhere pretty fast too.but being serious if your worried about fuel mileage a diesel might not be for you,sounds like you might be on a budget and budgets an $45,000 trucks usually don't work.

Thanks, thats the kind of info I'm lookin for. I want the power of the diesel, and almost anything will beat the 14 mpg I get out of my truck now.

I've done my research on what I want price wise, I'll be walking away financing under $25k with my down payment, trade in, and GMS pricing.

[ZsevneeONE]

Thanks, thats the kind of info I'm lookin for. I want the power of the diesel, and almost anything will beat the 14 mpg I get out of my truck now.

I've done my research on what I want price wise, I'll be walking away financing under $25k with my down payment, trade in, and GMS pricing.
yeah if you finance 25 then it won't be bad,the note will be between $450 an $550 depending on the interest an all that crap.i financed 24,500 an my note is only $440 with Gap coverage.I say get it because diesels are so fun especially when they are fast.

[dozerboy]

Your going to have to return the truck back to stock before you go to the dealer.

[ZsevneeONE]

yeah most definitely,they don't let you get away with any kind of tuner.

[MoJoe]

Doc, I love my new LMM. This truck has loads of power right out the box, and my mileage after 7k trouble free miles is at 17.3 mpg overall mixed driving. That is hand calculated and my worst tank was 14.7 while towing 9k lbs up to PA and back.

Regen does affect your mileage while in regeneration mode, but it normally happens once per tank of fuel and last for around 20 minutes with my truck in stock form. You can't even tell when driving.

There are 4 options right now for deleting the DPF. You have EFI Live, HP Tuners, PPE, and Quadzilla. Out of the 4, Quad and EFI are the most popular, and both work great. If you plan on running any heavy aftermarket tunes and do not want to affect regen frequency I would suggest deleting the DPF completely and use one of the tuners that kill the regen function, but keep the DPF on hand for warranty work. You want to be able to return it to stock. Any turbo back system will work on deleting the DPF from 01-UP. Last but not least, dieselplace.com has tons of useful info for removing the DPF.

Bottom line is I love my LMM as do 99% that own them, even with the new emissions crap it is a power house, and tows with perfection.

[ZsevneeONE]

yeah also the great thing about EFI live is it doesn't effect anything like your remote start an all that i've heard others work great but sometimes you can't use your remote start with them.my friend has the 500hp EFI live tune an it is plain crazy how fast that truck is,only problem is he twisted his driveshaft like a pretzel already.

[down4bmx]

Yeh I got an 2007.5 and I have put a turbo back exhuast from a 06-07 Duramax on there and the check engine will come on soon as the truck starts right up! But to get rid of the lights and regen mode you need efi, quad, ppe, or hp tuners, Im currently running the quad on 110Hp and No DPF tune and man does this truck light them up! Probbaly not to good on my tranny but what the hell I work at a chevy dealership ill just get it warantied ;) ahahhaha

[Tom S.]

Diesels only come with 3:73. You can change it after buying ($$$$).

You can get the gasser with a 3:73 or 4:10.

[JJ 05 HD]

If you order your truck, you can order it with a 4.11 even the 08 gassers are coming with 3.73's where in the classic's they came with 4.10 standard

[Big Angry]

If you order your truck, you can order it with a 4.11 even the 08 gassers are coming with 3.73's where in the classic's they came with 4.10 standard
That's news to me....I've been hearing since 2001 that "you can order 4:10s" or "my buddy knows a guy that got one with 4:10"s. If you get a Duramax with an Allison, it only comes with 3:73s from the factory, period. Until someone shows me a build sheet with the RPO's LB7 or LLY or LBZ or LMM and GT5 on it from the factory it will remain an urban legend.

[DrHolliday]

That's news to me....I've been hearing since 2001 that "you can order 4:10s" or "my buddy knows a guy that got one with 4:10"s. If you get a Duramax with an Allison, it only comes with 3:73s from the factory, period. Until someone shows me a build sheet with the RPO's LB7 or LLY or LBZ or LMM and GT5 on it from the factory it will remain an urban legend.

I test drove an 05 Dmax/alli combo with 4.10's. Think it was special ordered just for towing, but it didn't make since to me plus they wanted way too much for it.

I decided to go used instead of new. Found an 06 LBZ with 6 speed alli, bought it with 19k miles. I really love the truck, already has 23k miles on it.

[JJ 05 HD]

hope what I said didn't confuse you. I when I was shopping for my 05 6.0l gasser they came standard with 4.10's, Diesels all had 3.73's standard. Now in 08 the 6.0l gassers come standard with 3.73s just like the LMM's with the option of going 4.10's on both. I ordered a 08 GMC 6.0 and ordered it with 4.10's, then got rid of it for my LMM which has 3.73s standard. And if you dont believe that you can get the diesel with 4.10's go build a truck on chevrolet.com and you'll see it is an option you can select with LMM

[Big Angry]

I test drove an 05 Dmax/alli combo with 4.10's. Think it was special ordered just for towing, but it didn't make since to me plus they wanted way too much for it.

I decided to go used instead of new. Found an 06 LBZ with 6 speed alli, bought it with 19k miles. I really love the truck, already has 23k miles on it.
Congrats on the new purchase....but how do you know the 05 had 4:10's? Did you see the build sheet? Was the RPO GT5 in the glovebox? Not calling you a liar, but I think you were fed bad information. Still haven't seen a 2500HD or 3500 with anything other than 3:73s, a few claim to have them, but no one has proof. Until I see that proof, I think there is some bad info floating around. Enjoy your new truck, you'll love it!!


hope what I said didn't confuse you. I when I was shopping for my 05 6.0l gasser they came standard with 4.10's, Diesels all had 3.73's standard. Now in 08 the 6.0l gassers come standard with 3.73s just like the LMM's with the option of going 4.10's on both. I ordered a 08 GMC 6.0 and ordered it with 4.10's, then got rid of it for my LMM which has 3.73s standard. And if you dont believe that you can get the diesel with 4.10's go build a truck on chevrolet.com and you'll see it is an option you can select with LMM

You didn't confuse me. Configuring a truck on line is one thing, getting it to show up built w/4:10s or 4:11s from the factory is another. Call me a chronic skeptic, but until I see the glovebox with the RPO LMM and GT5....still not buying it.

[DrHolliday]

Congrats on the new purchase....but how do you know the 05 had 4:10's? Did you see the build sheet? Was the RPO GT5 in the glovebox? Not calling you a liar, but I think you were fed bad information. Still haven't seen a 2500HD or 3500 with anything other than 3:73s, a few claim to have them, but no one has proof. Until I see that proof, I think there is some bad info floating around. Enjoy your new truck, you'll love it!!

I didn't look at the build sheet. I had drivin a couple 5 spd and 6 spd alli trucks tryin to find the one I want. After driving this one, the tach read 2,000 doin 45-50. Had it up to 55 and it just kept climbing. The truck had 285's on it, it could have been that the previous owner changed the ratios, but 2k on the tach doin 50 seemed higher then all the other trucks I had drivin. I asked the salesman if it had 4.10's, but he didn't know, he said he could find out. I told him not to bother, I didn't want a truck with 85k miles for $32k.

And I do love the new truck, loads of power, plus I drive it easy most of the time and average 17-18 mpg on winter fuel!

[Racking9398]

it probable didnt go into overdrive. I know with the T/H button it want go into OD till 60mph

[Big Angry]

Or if the tranny isn't warm enough, my torque converter won't lock for a while, and I always tach higher until the TC locks in 5th.

[foreman00081]

Or if the tranny isn't warm enough, my torque converter won't lock for a while, and I always tach higher until the TC locks in 5th.

thats what i was thinking too, mine does the same thing untill it warms up. and ive also never seen a dmax with 4.10's stock. everything ive ever heard or read says that they were never offered with anything other than 3.73's. as much as these trucks can pull with 3.73's there would be no reason for 4.10's, it would just kill fuel milage with 245's. would also seem like it would put the motor out of its powerband. i guess you would have more torque at a lower RPM but would the turbo even spool down at say 1500 RPM's or less to give you that power?