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Discussion Starter · #1 · (Edited)
Have friend who just bought a used 2006 GMC Duramax. I was looking in this site to help him determine how to tell if he has an LBZ or LLY. I know I saw this years ago when I first joined this forum but can't seem to find it using "search".. Believe it has something to do with the VIN.
 

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Look at the 8th digit of the VIN number, a "2" is an LLY an a "D" is an LBZ.


Also, the LBZ badges are usually blue, LLY is usually red.
 

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Discussion Starter · #3 ·
Thanks, I knew it was something simple.
 

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Look at the 8th digit of the VIN number, a "2" is an LLY an a "D" is an LBZ.


Also, the LBZ badges are usually blue, LLY is usually red.
The LBZ badges say duramax allison LLY just say duramax
 

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If its a 2006, the "LLY" is just an LBZ with different tuning. You'd have to know the build date of the truck.

You also cant see the VIN section any more because you do not have enough posts. The rules were changed last year to 25 posts and one month membership to see that section.
 

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On the air filter cover it tells you the rated horsepower. Lly is 310, lbz 350.
 

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On the air filter cover it tells you the rated horsepower. Lly is 310, lbz 350.
LBZ is 360HP (stock), not 350. Easiest way to tell at a glance is to look at the door emblem. 2006 LLY says "DURAMAX Diesel" in black/red, which is unchanged from the earliest LB7s. 2006 LBZ (as well as all newer models) says "Allison DURAMAX" in blue/black. Of course the door emblems can be changed but the VIN doesn't lie.
 

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My '06 LLY says, "310hp at 90mm3" What does the LBZ say?
 

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Discussion Starter · #9 ·
All of this has really been helpfull and true as far as confirming that this is an LLY. Thanks a lot guys!!
 

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Scotsman, now to stir the pot, if it has a 6 speed transmission it is an LBZ, just with the LLY label as GM was revealing their "new" engine to be more in line when Ford and Dodge did so. If you download the tune in the ECM and compare it to one from a "D" VIN truck you will see the tables are identical, and even though it has a "2" in the VIN it has 360 HP.
 

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This has always stumped me. I have an 06 vin code "2" and black and red door emblems but I also have a 6 speed allison with the manual shift mode. So I assume it's just a LLY with a different tune, but mechanically they are they same? Is this correct?
 

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You have an LBZ, same mechanical engine, same tune (I pulled mine from the ECM and compared it to a "D" VIN truck and they were identical) it just was still called an LLY until GM announced the new engine. Yes the tag on the air cleaner reads 310 HP, if you ever get the chance test drive a classic body style '07 and compare the two.
 

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Is the "pedal position to desired torque" the same as well? I know my VIN 2 '06 had a 605ftlb as the max on that table. I know the fueling tables are the same, but I think they are artificially limited by this table.

Of course, I could be wrong (routinely am according to my wife) :)
 

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Hummm - I have no idea, cant say I even saw that table to tell you the truth, will have to pull my tune up and look at that.
 

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BTW, glad you got the tranny cooler problem fixed :)
 

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Thanks - well I think it may be plugging up again, so I suspect its the torque converter, one of the posters said the plugging would stop when the "paper" stopped tearing - any idea what all that is? I am going to bring it to an Allison shop and see what they think.
 

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THAT is an area I know precious little about. I have heard some guys running the LML T/C.

I do know that I can hear the T/C slipping when it is locked with my higher power tunes and high gears. That will be my next upgrade. The T/C for sure, but want to build the tranny as well. I found a nice kit for about $2800 with the T/C that's good to 1000HP, and I would like to do it myself, but I am a little scared to.

Just out of curiosity, since you do alot of towing, what gear do you normally tow in? I have played with both fifth and sixth. The truck seems to like fifth better. Lower EGT's and the like.

I tow a 9000# travel trailer at a whopping 10.5 MPG! Working on a tune for better towing mileage, but so far it has eluded me.
 

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On the big road I usually tow at 63 MPG in 6th gear,in big hills in CO or out that way I may drop it down to 5th, goose neck horse trailer, weighs around 16,000 lbs, 11'6" tall to the top of the hay rack, I see between 10.5 loaded and 13 if it is empty - 8,000 lbs trailer weight. We also have a 37' travel trailer that weighs around 7,000 lbs and I barely get 10 MPG when towing that, I think the difference is in the wind profile as the TT is like towing a giant wall, guess it would help some if I would remember to use the leveling bars when I hitch that up, spoiled by the goose neck for sure.
 

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The 8th digit in my VIN is a D so I have a de-tuned LBZ, I'll stick with that for now until I take care of basic maintenance and some work on the bed, interior etc. but eventually I'm going to want to unlock more HP and torque since I'll be primarily using the truck to tow a 36 foot fifth wheel at 13,000# +/- loaded. I'm not looking to race the truck or anything like that so does anyone know the best / cheapest way to get the LBZ tune on my truck?
 

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The 8th digit in my VIN is a D so I have a de-tuned LBZ.
You have an LBZ

You must of missed this.
Post #2 Look at the 8th digit of the VIN number, a "2" is an LLY an a "D" is an LBZ.

More info
Engine - How to ID a LBZ vs LLY
https://www.dieselplace.com/forum/6...how-tell-if-my-truck-lly-lbz.html#post7176234

Engine Differences LBZ vs LLY
https://www.dieselplace.com/forum/6...7-5-lbz-lly/67521-06-lly-lbz-differences.html

All this info and more here. LBZ/LLY FAQs
https://www.dieselplace.com/forum/6...ed-questions-faq-updated-december-2015-a.html
 
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