Before I order my 2500HD...

[Grouperassasin]

Glad I found you guys on here! This is my first post on the site, I hope it helps! I'm looking at ordering a new 2008 GMC 2500 HD. I am in the construction buisness and my Yukon is just not cutting it anymore. I have some questions that when I ask the local dealer, I'm not so sure they really know what they're talking about, hopefully someone on here does. Any help would be greatly appreciated.

Is the 6.0L V8 available in the HD with Active Fuel management? IF so, how do I spec it on my order?

Why does the trailering capacity drop almost 3000lbs when you select 3.73 gears vs 4.10 in the gas motor? I want the better economy of the 3.73 rear end, but don't know if I want to sacrafice what the truck is really meant to do.

what is the difference in fuel economy for the 3.73 vs. the 4.10 if all else is the same?

Thank you in advance for anyone who has the time or knowledge to help out, it's a large purchase that I plan on having for a long time, just want to make sure I order the right truck. Thanks again!

[gm4life]

Well I don't know as much as some of the truckers around here do. But basically I can say my uncle has a 2000 Dodge Ram 5.9 Magnum V8 and 4.10:1 and it is bad on gas 12mpg hwy. and 8 is town. I would go with the 3.73:1 just for the gas bill savings. I don't think getting the 3.73 is sacraficing what the truck is made to do unless you plan to tow a huge trailer or boat and need the extra towing ability. It also depends on what trim, 2wd or 4wd and bed/cab config you go with. Please post those details to help give us a better idea. The economy gap will be noticable not huge but you would be able to tell, with the 4.10:1 you will have more off the line giddy up especially with the new 6 speed automatic with the gas and Duramax motors. I haven't driven a new GMT-HD yet but I bet with 6 foward cogs they are fast and that will aid in fuel economy. It really all depends on what you want to do, if you just wanna load the bed up go with a 3.73 and tow a trailer within the towing limits if you towing all the time and towing huge loads opt for the 4.10:1. Good Luck and happy buying. Those trucks are VERY tough and refined, also the Vortec 6.0L with 352hp (est) in HD trucks doesn't come with AFM (Active Fuel Managment) at least I don't think so. Once again happy buyign and wait for a real trucker to give his 5 cents. (I own 3 GM cars! Not trucks lol.) Post photos of it when you get it! LASTLY WELCOME TO CHEARS AND GEARS! You have come to the right place!

[Camino LS6]

See my reply to this post in the tech section.

[Grouperassasin]

See my reply to this post in the tech section.

Thanks guys! I understand the basics of the gearing and know that it won't be as fast off the line or have the low end grunt of the 4.10 rear end, I was just shocked on GMC's website to see almost a 3000 lb drop in trailering capacity when you select the 3.73 gears with the gas motor. I don't tow at the limits of the truck that often, so I lean toward the 3.73 for the better economy, but if GMC's website is correct, the trailering capacity is no more than a Titan? I just don't understand how the gearing will drop the trailering capacity that much.

As for the Active fuel management, It was confusing to me when the GMC brochure says that the 6.0L is available with the VVT and AFM for the 1500, didn't know if it carried over into the 2500's also. It's on the page that talks about the 5.3 with the AFM and says, " if you need even more power, you can select the 6.0L with variable vale timing and AFM" Just needed some clarification?

Anyone know anything about the flex fuel option on the big boys?

I'm very excited, my buisness partner has a 2500 HD 2002 and that truck can definitely take anything you throw at it!

Thanks again guys!

[Newbiewar]

Thanks guys! I understand the basics of the gearing and know that it won't be as fast off the line or have the low end grunt of the 4.10 rear end, I was just shocked on GMC's website to see almost a 3000 lb drop in trailering capacity when you select the 3.73 gears with the gas motor. I don't tow at the limits of the truck that often, so I lean toward the 3.73 for the better economy, but if GMC's website is correct, the trailering capacity is no more than a Titan? I just don't understand how the gearing will drop the trailering capacity that much.

As for the Active fuel management, It was confusing to me when the GMC brochure says that the 6.0L is available with the VVT and AFM for the 1500, didn't know if it carried over into the 2500's also. It's on the page that talks about the 5.3 with the AFM and says, " if you need even more power, you can select the 6.0L with variable vale timing and AFM" Just needed some clarification?

Anyone know anything about the flex fuel option on the big boys?

I'm very excited, my buisness partner has a 2500 HD 2002 and that truck can definitely take anything you throw at it!

Thanks again guys!

your all over the place...

Active fuel management... is a cylinder diactivation... (collapsable intake lifters) avalible on only a few engines... if you notice below, the intake is different between the two engines, and i believe the heavy duty to have cast iron heads, but i could be wrong... generally iorn is used for workhorse motors, that will take the abuse of day long hauls... they react to heat better, aluminum just helps keep it cool, but they cannot take the 260 degrees that an iorn motor can...

Flex Fuel, capable of burning E85... engines are the same... Ethonal, is an alchol that eats rubber, E85 requires plumbing to be reworked with a material that doesnt disolve, then gumming up your injectors... also the use of E85, will result in less fuel ecconomy (not what you want, nor most haulers)

Vortec MAX 6.0L V8 engine features: (1500)

Thundering 367 horsepower @ 5500 rpm

375 lb.-ft. of torque @ 4300 rpm

More horsepower than any half-ton engine offered by Ford, Dodge or Nissan(1)

EPA estimated MPG 13 city/18 highway in 2WD models

EPA estimated MPG 13 city/17 highway in 4x4 models

High-speed air movement deep inside the combustion chamber, which generates a better fuel-to-air mixture

Variable Valve Timing (VVT) technology that optimizes combustion, enhances low-end torque and high-end power, promotes fuel efficiency, and helps lower emissions

A cast-iron crankshaft with undercut and rolled fillets

High-flow cast-aluminum cylinder heads that feature a low-friction roller-rocker valvetrain

Electronic Throttle Control that provides outstanding throttle response, greater reliability and improved efficiency

A fast, smart Engine Control Module with plenty of memory synchronizes the multitude of engine operations that occur every split second

Hydraulic engine mounts for improved vibration isolation

A coil-near-plug ignition system for a precise delivery of high-energy spark

Vortec 6.0L V8 engine features: (2500)

Thundering 353 hp @ 5400 rpm (312 hp @ 4400 rpm in 3500HD Big Dooley models)

Class-leading standard heavy-duty horsepower in 2500HD and 3500HD Single Rear-Wheel models(1)

373 lb.-ft. of torque @ 4400 rpm

High-speed air movement deep inside the combustion chamber, which generates an ideal fuel-to-air mixture

Variable Valve Timing (VVT) technology that optimizes combustion, enhances low-end torque and high-end power, promotes efficiency, and helps lower emissions

A cast-iron crankshaft with undercut and rolled fillets

A thermoplastic composite intake manifold that helps keep the air intake cool, and equal-length runners that feature smooth interior passages to promote high-speed airflow to each cylinder

Electronic Throttle Control that provides outstanding throttle response, greater reliability and improved efficiency

Hydraulic engine mounts for improved vibration isolation

A faster, smarter Engine Control Module with more memory that better synchronizes the multitude of engine operations that occur every split second

A coil-near-plug ignition system for a precise delivery of high-energy spark

This of course all thanks to CHEVY.com

as for the ratings... when payload and other load bearing ratings are developed, they are the vehicles rating of the weakest link... many times the motor the transmission brakes can handle 25,000lb trailor, perhaps not with the same enthusiasm.

but things to consider are axels, brakes, driveshafts, differentials, transmissions, engines, cooling systems, and frame... perhaps i missed something... but when certain equipment is put on vehicles, sometimes other equipment is packaged with it... on my 3500 8.1L i've got 4.10's i dont beleive the 3.73's are an option... but sometimes with a different differential, you might get a bigger axel, bigger brakes... who knows...

my parents had an old F350, and when fully loaded... sometimes it had trouble going up hills... one in particular, if the truck was overloaded, we'd have to take the horses out of the trailor and walk them to the top because the truck just couldnt accelorate... once they replaced the rear end with a lower end (either 4.10's 4.11's or 4.56's i forget) it had no trouble hauling the same weight up the hill... but the point of the story, isnt that fords suck, we have newer and more powerful trucks... its that sometimes, that 200$ option could save you a lot of hassel...

[Grouperassasin]

Newbie,

Thank you kind sir! Best explanation I've gotten so far! I just posted in the Tech section about the rear end gearing and if I need to pick the 4.10 rear end since I'm going to lift the truck and run 35" tires on it. Any insight yo have would be much appreciated! Thanks for the clarification on the other items. I appreciate all your help!

[Newbiewar]

Newbie,

Thank you kind sir! Best explanation I've gotten so far! I just posted in the Tech section about the rear end gearing and if I need to pick the 4.10 rear end since I'm going to lift the truck and run 35" tires on it. Any insight yo have would be much appreciated! Thanks for the clarification on the other items. I appreciate all your help!

well if you are going to increase the size of your tires, you are actually reducing your power by increasing distance traveled per rotation of tire. so if you add 35's you will be better off with the 4.10's in my opinion...

keep in mind, on all vehicles, mud tires, or oversized tires, generally consume more fuel and make an annoying noise (in my humble opinion any way) also sometimes if done inproperly i've seen the tires rub on the sheet metal around the front tires or the plastic or whatever exposed material... just keep in mind not all lift kits and oversize tires that fit are what you want... being at the dealership i've seen many shotty jobs, so just be careful.

so... thats all up to you, if i were your salesperson, i'd urge you to get it packaged into your loan, so i could make the commission, but i'm not the salesperson, i'm trying to answer your questions so that you may make the decision... i'll say this... you cant go wrong with the 4.10's... although you might bring a knife to a gun fight if you get the 3.73's... but only you know how much you load your vehicle down...

most times the vehicles (expecially gm's) ratings are what lawyers are comfrotable advertising... not necessarily the trucks capability... my 3500 is rated for 6000 lbs in the bed... i beleive that and more... i've sold a customer who added a 2000 lbs wood stake bed... and then puts 8000 lbs on top of his 3500... so if you think of that payload of 6000 lbs, and think that i've got people putting 10,000 lbs on it on a daily basis... GMC's and Chevys make hell of a truck...

[Camino LS6]

Probably not what you want to hear, but I would not lift the truck. At least drive it for a while and think it over. There are a whole host of good reasons not to do that.

As far as the gears go, the 4.10 is a great choice if you don't mind paying for the fuel. The 3.73s wouldn't disappoint either, but if you add 35s to the truck, the 4.10 would be a better choice. If you decide not to lift the truck, the 3.73s get the nod for improved MPG.

[Grouperassasin]

Newbie,

I agree wholeheartedly on the ratings being only what they can safely put on there in our sue happy world we live in. I fully believe that they are the toughest trucks built by far, hence my soon to be purchase. I am leaning toward to 4.10's, just so I don't regret it. I own a construction company, so while the slightly increased fuel cost will suck, it's still a write off, and I don't want to be changing out the gears later casue I'm having trouble pulling something.

Camino,

I will drive the truck for a little while, but I'm 99% sure that it's going up. I'm on construction site's all the time, and spend quite a bit of time outdoors on my free time. WHile I'm not going incredibly high, the extra ground clearence and wider contact patch does help on a daily basis. Four Wheel parts is the company that is going to be doing the lift, and I'm leaning towards the Pro Comp kit. ( same kit my buisness partner has on his '02 2500 HD and the same one the dealers in our area put on the trucks they sell already lifted ) I'm only going 6" up and 35" tires exactly for the reason that I want to maintain ride quality and functionality. If I wanted it to ride like garbage, I'd have just bought a Ford and been done with it. I'm putting the Toyo Open Country Tires on it, no mud terrains here, so the ride should still be quiet and smooth. I drive over 20K miles a year, so it needs to be still be somewhat domesticated. I have gone out and rented a 2500 HD and driven it for several days to make sure I liked it and how the handled, manuevered, etc. Only thing now, is waiting for GM to build the damn thing, I'm going to order it on Wednesday. And I have to figure out a way to make it easy on the wife to get in and out of, she's only 5'2"! Thanks for all your help guys! I'll post pics once it gets here.

[Camino LS6]

Looking forward to the pics!