Spied! HD Pickups Show Tailpipe Changes

Cdoane GM HD II

Photos by Chris Doane Automotive

Our spies are everywhere, even places you wouldn't expect to find much information. In fact, during a recent catch of a fleet of various heavy-duty GM trucks being tested in Michigan (similar to those spied a few weeks ago, our shooter noted some multistate plating that could mean there are some additional powertrain alliances coming or more significant changes in store.

In the past, catching a camouflaged pickup truck with Indiana plates (usually a Ram HD) meant that Cummins was testing (its headquarters are in Columbus). What's unique in these photos is that the exhaust tips show two different types of tailpipe tips (see below). Yes, they both have the open venturi flange to help cool exiting exhaust temperatures, but the Michigan-plated truck is a little different.

The bottom Indiana-plated truck has the conventional-looking Duramax tailpipe, while the top one has a more custom-welded "straight-pipe" look and what looks like an added sensor on the rear differential drain plug, presumably for keeping track of oil temperature. We should also note that Allison Transmissions has a facility near Indianapolis and could be testing a stronger, heavier-duty transmission for the next-generation HD trucks that some are saying will be out in 2015.



Nothing meaningful here...move along

I bet the top tail pipe is to throw off spy pics. If you see it in passing you would think it's just a gasser.

We know what they look like so why the truck burka? Tailpipes are tailpipes, but what's with the "Rancho" shocks?"Is this finally an answer to the Power Wagon and Raptor?

Receiver looks small for these Sierra HD's.

Is this finally an answer to the Power Wagon and Raptor?

LMAO, GM has no answer for the Power Wagon or Raptor, never has and never will. Unless you consider Z-71 stickers their answer....

@TruckGuy | How dare you??? That AMAZING Z-71 sticker-package used the ABSOLUTE best vinyl and adhesives known to man! Seriously though, any mild off-road package 'betters' the sport for all involved. Even chicks with wallet chains.

Aftermarket off-road 'anything', would be a 1st for GM.

Still has that low hanging frame

Trucks have to change in the Us future & this tale pipe could have to do with whats under the hood.Smaller,more torque,more mpg.

Why does Ford and GM use the venturi on their tail pipes but Ram doesn't?

TruckGuy.... great post! I think your right, the Z-71 stickers is GM's answer to the Raptor and Powerwagon! LOL

@Billy | That low-hanging frame is an essential part of the ultimate off-road package. The frame rails protect the trans pan, transfer case, drive shaft and exhaust. Of course it protects the body too.

I don't like taking away the competitions achievements to make my favorite brand seem superior so I don't understand why some of you say GM has never had the answer for the Raptor or Power Wagon when GM had Hummer. The question is not if GM could make one but if it is in their corporate strategy. The Z-71 package much like the TRD Off Road package is not the best they can do when they make the Land Cruiser. I would say Hummer and Land Cruiser were 2 of the best factory off road vehicles ever. I will use my truck as an example we all know I love my Supercharged Tundra which is currently the fastest 1/2 ton still with a complete manufacturers warranty does that mean Ford can't develop a faster Lightning, or Ram something new from SRT or how about a faster new SS it just means right now it is not the competitions corporate strategy.


It's the legend in off-roading!


"You can get good lookin' and comfortable. You can take it through the woods which is kind of the total package!" - Howie Long

@AD | What was different or better on the H2 Hummer vs a Tahoe? When it came to off-road ability/performance?

Here is a link for some to learn from on exhaust systems.

Exhaust systems are critical and impact the performance of an engine, any engine.

So, for the guys that go out or want to drop a new system on their pickups should have a read, it could change your mind on what direction you will head in.


Each of the big 3s strategy is not to have an answer for every vehicle the other has but just those they think will sell.

I agree with Big Al every thing has a purpose & with all the electronics on todays vehicles you need to research before changing.

I see the H D trucks getting bigger & going almost all diesel but the family U S trucks will get smaller.I think 2 of the big 3 missed the boat by not bringing over the smaller Global trucks.I would love to know how the Colorado is holding up over seas.They are all good looking trucks & a shame we do not get them all over here.

@Ramman - The exhaust on the Cummins engine must run cooler. Maybe something to do with DPF. Just a hunch.

We've seen odd exhaust tips on test trucks before. Could mean nothing more than a mod for attaching testing equipment.

Deaver Mike, biggest difference would be much greater ground clearance, much better approach and departcher angles and bigger tires at least compared to stock.

IIRC, the original HUMMER was not a GM product. It was made by AM General for the USA army. AM General sold the name Hummer to GMC which marketed the civilian version as the H1. They released the H2 on a Tahoe SUV platform and the H3 on a Colorado platform.
GM could make a Raptor "like" or PowerWagon "like" truck but unfortunately would be labelled a copycat. There isn't any halo product benefit for GMC to build such a truck due to that stigma.
A diesel Colorado with Hummer H1 off-road suspension ie. portal axles would be one way to carve out a niche market of their own.
A diesel 3/4 ton like their concept "All Terrain" might be able to avoid the copycat label.

Nice low slung frame they have there. lol! Drop it a few more inches and you'd have a nifty sparkler machine when it gets dark. That looks terrible. As always. No ground clearance either.

That Howie Long Z71 video is hilarious.

@Billy, that frame dropped down low has nothing to do with off roading. Dodge and Ford are the off road kings and they don't have it. Old Chevy's from the 70's and 80's are common off road trucks and they don't have it. Those frame rails aren't to protect anything. They're so the torsion rods can tie in straight from the lower control arms from the front wheels horizontally to the frame for support. Since the control arms are inches from the dirt, the frame rails likewise have to be. Horrible horrible design.

The pipe extension might be to test a different location of the venturi. If cooling fresh air is added elsewhere in the exhaust, perhaps in the slipstream under the truck, it might provide a more visually appealing exhaust tailpipe.
@ AD and Bing back Howie Long
I will put my stock factory built Off-Road package truck against any stock GM Z71 truck or any stock H2 or H3, any day. I told Terry Woychowski and Jim Mikulec this directly. They offered to let me run the test track at the YPG, but as of yet I haven't seen any of them take me up on it. Perhaps because they know that I know Thad Stump and that one day while scouting for Javelina, I met up with a Mesa-DPG team and ran the same trails on which they tested the H2 and H3 engineering mules. (Remember, these were the GM Off-Road trucks) Eitherway, if you want to buy a GM truck by all means. There are plenty of reasons to do so, but they are NOT GOOD OFF-ROAD IN STOCK TRIM, even with the Z71. There is a reason they keep showing the same muddy run over and over and that there are multiple tracks through that mud. The GM HDs aren't designed to be used in any serious off-road scenario. There are warranty limits on tire size/height; the front fender width and bumper placement is done intentionally to require either cutting of the fender/bumper air-dam and a lift to fit larger tires. The torsion bar adjustment will work to get the largest tire they will allow, but it doesn't fill out the wheel wells or off-set the low-stance of GM trucks. Sadly only with some stronger half-shafts and tie rods, a mild lift (or cutting) and some larger tires, will the GM trucks are decent off-road. Most folks that use their trucks off-road either buy a GM truck with the intention of modifying it, or they buy a Ford, Dodge or a Tundra. Like myself, after a couple bad experiences with a GM truck, many switch to the competition.
I really like GM trucks, but for me and my life, the thought of buying a new truck, then immediately voiding the warranty by modifying it so it will work off-road is pointless.
And the Gov-Loc...aka the Eaton locking differential...They have a pretty legendary failure rate when used in heavy off-road situations.
But don't take my word for any of this, do your own research.
If you want a GM truck and this doesn't matter, by all means get what you want! But if you are looking for a truck you can drive to work, tow your trailer, and run in a genuine off-road situations, you'll be much better served to buy a competitor.

@don nc
The Colorado is selling reasonably well in Australia, do not know about other markets though. Agree HD Pickups will go almost completely diesel.

Robert Ryan How are the Colorado 2.8 diesels holding up & is this a new engine or one that has been around a while.

These guys really need to go back to a tucked up straight frame rail set up and a swing arm-coil SFA. Just do it right and be done with it. I can't imagine how many 25-3500 customers they lose over all of this. Their HD trucks are pavement pounders of the strictest definition. And I'm still telling you, now that they use stiffer torsion rods to carry heavier plows on the front ends, these things ride Terrible. I wouldn't even want one on pavement now. My Super Duty rides like a Cadillac in comparison. They have some Great powertrains in Chevy's. I love Chevrolet engines and the Duramax diesel. Ford and Dodge are building great powertrains now though too so it's almost a wash in the powertrain department. That's when it comes down to the rest of the truck in terms of build quality, overall design and suspension design. These are the areas Ford and Dodge have it all over Chevrolet.

And yes that frame is an eyesore. They always have been since the early 90's when they went to that design. They look even worse once they get all rusty. And GM frames are the worst for getting covered in rust these days because they don't properly paint them. That cheap wax dip is good for a couple of years if you're lucky. Ford used it for awhile too and went back to paint. They learned the hard way, GM is still penny pinching.

The Z71 package on my 99 2 door Tahoe included an extra leaf spring, skid plates, HD trans cooler, and a 3.42 G80 locker. Though I believe that locker was an option on it's on.

Even with the Z71 Package the 99 Tahoes were not decaled as Z71.


GM might lose 20 customers because of their suspension setup and that is just to some poser tough guys who "think like you" that a sfa is end all and that they need insane off road ability when in reality you never take that damn thing off road. It is just easier to have a street queen lift put on like all the lifted trucks you see anyways. All you are doing is putting the label of an sfa from a jeep because it is the off road king and think if you put that same axle set up on these trucks you are a man and can conquer any off road situation. If you do then buy a dedicated off road truck and quite justifying a one ton for off road duty. Gm trucks are just as capable if not more so in the real off road situations a one ton truck would face, which is a logging type road towing a trailer or loaded down with crap in the bed on the way to the job site. I have multiple friends who have company one ton 4x4 trucks and they are loaded down with 3-4k lbs of work equipment or towing trailers to their next site and guess what these trucks are doing? Surprise surprise they aren’t crawling around moab but they use them to get to remote sites in fields, down back roads and around lakes. YUP, SFA is needed there so bad. Two have fords, three have chevy’s, no dodges. But dodges have SFA so they should be king and you shouldn’t look at GM says off road kings… Get real, towing and hauling #’s matter more. GM sold more ¾ tons and damn near more HD’s in total, so they must be doing something right, looks like there is a smart customer base out there that doesn't think HD pickups should be jeeps.


Well said Tyler.
FordTrucks1, real life F@#$%Troll1, is just that!
It's funny how he bashes Chevy, but always adds something nice about them, usually something about engines, so he won't get harassed by Chevy guys after he posts (always the same thing) his nonsense.

One phrase for you "FX4" Chew on that!

I don't know why they bother putting all the padding on the test truck. It only draws attention, and theirs so little changes that most people wouldn't notice it otherwise.

Isn't the Duramax slated for a clean sheet redesign soon? I am assuming we are seeing that motor in one of the trucks and the 6.2 in the other. Should be a stout combo of power and solid tranny work from Allison.

I expect the frame to be a carryover since it was "all new" last year but the look outside and inside better be much better. I have commented before that I like the outside look of the new Silverado (Sierra is too blah and basically looks the same other than some LED's to my eye) but the inside that was supposed to be light years ahead is only up to snuff. Maybe GM can introduce some differentiation since these trucks still have 12-18 months before they go on sale.

Well said Tyler and GregoryJ. FordTrucks1 and all of his aliases are a total crock. He really needs to come up with some new material because he flat out sounds like a broken record. You would think he would get tired of posting the same crap over and over. I bet he has a template post pasted to a Word document on his desktop, so he can cut and paste the same posts over and over again. Even Michigan Bob was more interesting than this guy.

Honestly .. Me and my friends have 94,95 and ,97 Gmc sierra's and they are doing Well Good when come to off-roading .... even if its not a (SFA) they are Torsion bars and really doing good i dont know why people complains about Gm torsion bars ... they are good Off-road and On-roads .. i pull out alot of time my friend father Dodge rams 2500 HD 2001 in snow so please just Dont buy GM's product if you dont like it .. stay with youre ford's and dodge's trucks we need these BIG Three because its good for us and the competition ... imagine if i exist just one brand ? it will weard and no competition .. i like both three but prefere Gm and othe prefere Ford rams and toyota's

If you are doing Rock crawling then dont buy a brand new truck ! its for rock crawling i never see people buy a new chevy truck 2500HD or a Ford f-250 for rock crawling .. theres some of those but they just put a SFA on a GM truck and its all Good stuff Geez

if you have enough money to spend to buy a brand new truck for off-roading then you have enough money to buy a solid front axle on gm truck

@don nc
New Engines for the Current Colorado seem to be OK. The Isuzu twin of the Colorado has an Isuzu 3 Litre.

Gm have no reason to build a raptor,,,keep ford play in the sand..

The exhaust tip on the GM and Fords are an emission control device's to help pass EPA clean air regulations.

I.E. Add more air to the exhaust you get a cleaner test results on the emissions testing equipment.

that tail pipe looks no different than the ones used in the current duramax trucks.

They don't have much reason to keep the cab covered...it's not like it's much different (if at all) than what we've seen with the 1500's. Or even the bed, for that matter.

HAHAH! Even that ford geez look this SFA! haha http://www.youtube.com/watch?v=4KX93fGc92Y

So much misinformation finally gets me to speak up. IFS will eventually show up on rear suspension also. I have GM at the moment, I have owned all 3 brands. I am really going to hit Dodge, which was the last I switched from. They don't make their tranny in the heavy duty. They don't make the engine in their diesel and they don't even have an American owned company. You boys are buying Italian. Man that should make you sick. The new (Ram) had to use exhaust fluid in that ancient farm tractor six cylinder. It still can't produce 400 horse power because the torque drops too fast at high RPM. I know torque and horse power can be confusing to many, but look what happened in all the king of the hill competitions. You can spin your wheels off the line and as soon the RPM gets into the HP range you loose out. That is written in stone, because horse power is the rate of getting work done BOYS. You don't idle up a hill with a heavy load, you punch it to the floor and shift into successive gears at high RPMs and never see that super torque at idle again. Too bad six cylinder diesel! OH and I forgot! The military 6 and one half ton super truck has independent suspension all around. That's right, even on BOTH rear drive axles. I agree with one difference on GMs IFS, they never made it heavy duty enough till maybe now.

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