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Discussion Starter #1
Wasn't planning on buying a truck but I just ended up with a 2001 3500 4x single cab dually. It's a 100% stock LB7 Duramax with the ZF 6 speed manual and only has 40k miles on it. It came with a full B&W set up (companion 5th wheel)

My plan was to get a new (or near new) diesel to replace my 04 Cummins/NV 6 speed 2500 in a couple of years but I picked this up yesterday and if I can make it tow to my satisfaction I may just forget my new truck plan. I really like the idea of no truck payment and no DEF or pretty much any other emissions stuff on this truck.

I was thinking air filter/intake, exhaust, tuner, and gauges (EGT & boost); likely a Pacbrake if it all works out. I don't mind upgradding to a dual disk clutch if needed (did that on my Cummins/NV 5600).

Has anyone gone down this route and has suggestions for what mods to do and what not to do? Tuner brands? Maybe a tuner that incorporates gauges?

Not looking for a hotrod, just significantly improved towing power levels. I live at about 6500ft elevation and my application will be towing a variety of trailers to include:
- 34' 5th wheel camper
- 42' Living quarters car trailer (5th wheel)
- Triple axle tilt bed goose neck
- 24' Enclosed tag car trailer

Hoping to learn from other's successes and mistakes :)

Thanks
Allen
 

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If you have trouble with the duramax expect way more labor than anything on a cummins..That year 6.6 wasnt that great compared to the new ones.Best part was the allison transmission but you have a manual.In stock form you should be ok for a 5 wheel less than 15800,thats the max rating.Lb7.
 

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Discussion Starter #3
If you have trouble with the duramax expect way more labor than anything on a cummins..That year 6.6 wasnt that great compared to the new ones.Best part was the allison transmission but you have a manual.In stock form you should be ok for a 5 wheel less than 15800,thats the max rating.Lb7.
I'll be pushing that 15,800 pretty hard, 5th wheel camper is under by about 1k but depending on what car is in the living quarters trailer, it could be closer to 16.5k. From a power standpoint, my Cummins 2500 does pretty well but from a load capacity and stability standpoint, it's not ideal or even factory rated nearly as much (19.5s and rear axle rating is in excess of need but truck rating is well below).
 

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To put it in perspective the 2021 DURAMAX offers 36000 pounds towing capacity.
 

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Discussion Starter #5
To put it in perspective the 2021 DURAMAX offers 36000 pounds towing capacity.
I get that, it also offers: DEF, electronic complexity (potential long term issues, I've had my current truck for 16+ years and will have it for many more), and a 70-80-90k price tag. Yes they are great (all the big three really) trucks with outstanding, even over the top towing and comfort. However I'm asking about how to improve on the LB7 platform I already have.

My original plan was to buy a new truck in 2023-2024 but I really would rather not; I may still go that route if I can't mold this truck to my needs or at least near to them. Sort of why I daily drive a 64 El Camino and not a new car, also why I modded my 64 to my liking/needs/wants (EFI 383/T56/AC/PS/PB/Tilt/tall spindles/big brakes/coilovers/etc...).
 

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Im a gm tech for 25 years ,im saying might not be a good idea to get more torque from your lb7.they are known for head gaskets and injectors ,the engine was much improved on in later years.You can get lots of upgrades like a bully dog,lots of people do upgrade these engines ,im more conservative cause i know these engines,A cold air intake and a mild program is as much as i would recommend for durability.
 

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Discussion Starter #7
Im a gm tech for 25 years ,im saying might not be a good idea to get more torque from your lb7.they are known for head gaskets and injectors ,the engine was much improved on in later years.You can get lots of upgrades like a bully dog,lots of people do upgrade these engines ,im more conservative cause i know these engines,A cold air intake and a mild program is as much as i would recommend for durability.
Thanks, that's great info.

I may do some test towing while it's 100% stock and gauge if a small improvement will fit my needs/desires; if not, send it down the road and stick to my original plan. Although I hate the idea of a new truck with DEF (potential large ticket repairs down the road) and all the electronics that I don't trust for long term ownership (15 - 20 years) I do like the loads of power on tap, bigger brakes, factory exhaust brake, ventilated seats....

I've been very happy with my Ram and like the new Rams (except the trans) so that may be the direction if I go new but how long will a 12" touch screen last and will I even be able to get one in 15 - 20 years? Other than brand loyalty, it seams like all the new 350/3500 trucks are pretty good. As a GM tech, maybe you see that statement differently?
 

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I just sold my LB7, wished I would have kept it. Bought a 19 3500, haven't towed with it other that a 10 mile test. My Lb7 was EFI live tuned, I ran 30 hp tune towing & it towed pretty good.
My 5th wheel grossed 14K. Exhaust & intake are pretty much a waste. I guess if you want the sound do ex.. I put 4" with a muffler on mine sounded good driving empty but towing droned real bad.
You should still be able to find tuners for your as there is no emissions to worry about.
You could try Kennedy diesel he used to do tow tunes with a DSP2 switch.
 

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Discussion Starter #9
I just sold my LB7, wished I would have kept it. Bought a 19 3500, haven't towed with it other that a 10 mile test. My Lb7 was EFI live tuned, I ran 30 hp tune towing & it towed pretty good.
My 5th wheel grossed 14K. Exhaust & intake are pretty much a waste. I guess if you want the sound do ex.. I put 4" with a muffler on mine sounded good driving empty but towing droned real bad.
You should still be able to find tuners for your as there is no emissions to worry about.
You could try Kennedy diesel he used to do tow tunes with a DSP2 switch.
Thanks, I'll check it out.

I just couldn't pass up a 43k mile truck, I'll do a tow test and get an idea if a small tune will get me to where I want to be or if I'll let someone else have her.
 

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Im a gm tech for 25 years ,im saying might not be a good idea to get more torque from your lb7.they are known for head gaskets and injectors ,the engine was much improved on in later years.You can get lots of upgrades like a bully dog,lots of people do upgrade these engines ,im more conservative cause i know these engines,A cold air intake and a mild program is as much as i would recommend for durability.
I just couldn't pass up a 43k mile truck, I'll do a tow test and get an idea if a small tune will get me to where I want to be or if I'll let someone else have her.
So if the late model engine is that much better what about the possibility of an engine swap ? would that help make up the difference between the early engines problems and the later models additional towing power.? Or would the new engines pricing put it out of the range of possibilities ?
 

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Discussion Starter #11
So if the late model engine is that much better what about the possibility of an engine swap ? would that help make up the difference between the early engines problems and the later models additional towing power.? Or would the new engines pricing put it out of the range of possibilities ?
I'm all about engine swaps (usually a big block ;)) but if I were to do a tow vehicle engine swap I'd likely do a Cummins swap. To justify the cost I'd have to really be attached to the truck (I'm not, at least not yet); funny, it's very easy for me to justify spending money on my old Chevys. I've always thought a modern diesel drive train in an old COE would make a cool tow rig
 

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That is pretty low mileage for that age of truck, the injectors can be problematic, might consider a set along with a mild tune and good luck!!
I recommend using a cetane improver at each fillup, you'll be glad you did, today's diesel is crap!!
 

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If you do injectors use SAC style, supposed to last longer.
 
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My buddies 2001 GMC has clocked over 400K. Allison just rebuilt. Stock engine tune and changes oil at the 80% used level. Anal about fuel filters. Still runs mint, although the rest of it is falling apart due to salt.
 

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My buddies 2001 GMC has clocked over 400K. Allison just rebuilt. Stock engine tune and changes oil at the 80% used level. Anal about fuel filters. Still runs mint, although the rest of it is falling apart due to salt.
How many injector jobs?
 

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Discussion Starter #17
My buddies 2001 GMC has clocked over 400K. Allison just rebuilt. Stock engine tune and changes oil at the 80% used level. Anal about fuel filters. Still runs mint, although the rest of it is falling apart due to salt.
That's impressive!
 

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I'll have to ask him next time we chat.
 

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Discussion Starter #19
To be fair, I had to replace the injectors on my 2004.5 Cummins at about 120k, regretfully it seams that injectors are somewhat a problem (apparently to varying degrees) for most of the later diesels. It wasn't too bad a job and I hadn't ran the rack in it so two birds so to speak. Of course I went with 50 over (new) injectors because I can't leave anything alone.
 

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LLY engine for my buddy, not the lb7; he had one injector go bad due to it rusting. The Allison crapped out at 168k btw.
 
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