I have a post about TV selection, and I still plan to purchase a heavier TV at some point. That being said, I am toying with the idea of picking up a travel trailer in the neighborhood of 4730 UVW/6800 GVW and towing with our 2015 Yukon XL. My Yuke does not have the heavy trailering package, therefore, it is downrated to 5,000 or 6,000 lbs depending on which literature I refer too (GMC trailer guide says 5,000, manual says 6,000). As far as I can tell, the only difference is in gearing and the integrated brake controller. So mine has 3.08's, and upgrading should put the rating at 8,000 if my thinking is correct. The heavy trailering package includes 3.42's.With all that being said, if I go this path for the short term, I will upgrade the gears, but would probably step up to 3.73's if I'm going through with it. That should be comfortable at the weights above and still repeatable cruising RPMs at highway with the six speed. Any thoughts on this? How are the thoughts in the stock anti-sway? Is an upgrade in order? What about airbags or other suspension thoughts?I will probably get an autocal tuner from BB so I can put it back to stock easily for service.Amy thoughts on stock CAI and exhaust? Are they fairly good or is there value in upgrading?Should I consider transmission cooler or any other accessories?

Before you did ANY mods I would really consider going back to the GMC dealer and getting some numbers on trading for a Yukon XL with the NHT trailering package. You get the HD cooling package, 3.42 rear axle ratio, IBC etc. You may be able to do this for very little difference on your Payment and have a really good towing platform. You can change the rear axle ratio on your truck now but you will risk the warranty. But that may be a minor consideration for you. Thanks!Jeremiah

I understand what you are saying. I'm not too concerned with the warranty with the mods I'm talking about. The only thing that I believe they would see and/or have a problem with is the tune. With autocal I can easily revert back to stock.

I would agree with Jerem0621 on this only I would go a step further and get the longer wheelbase Suburban. The longer wheelbase makes a better tow rig, more stable.

The Yukon XL is the GMC version of the Suburban. As opposed to the Yukon which is the sister of the Tahoe.

Even if you change gearing and get the PCM re-flashed for the new gears you won't have the heavy-duty cooling package.I don't know about GM, but rumor has it Ford can tell if you re-programmed the engine computer and then set it back to stock.

2015 Yukon XL | Good Sam Community

21 Replies

Dadoffourgirls
Explorer
Dec 14, 2015
If you are not headed for the mountains, you could tow the trailer you are describing. I am not a proponent of towing over rating, but I used a 5.3/6sp/3.08 to move my trailer a couple of times. The moving was between 10 and 50 miles. It was not fast off the line, but it worked.
Knminton
Explorer
Dec 14, 2015
Thank you, Wishin. That's exactly what I was looking for. Mine has the 2-speed transfer case.
Wishin
Explorer
Dec 14, 2015
From the GM order guide: HD Trailering Package includes (GU6) 3.42 Axle Ratio, (JL1) Trailerbrake controller, (Z85) Suspension Package and includes (NQH)transfer case, active, 2-speed with 4WD model

The HD cooling for oil and trans are listed as standard.

2015 Order Guide

What transfer case do you have? I'm not sure if the 2-speed is more heavy duty?

Also, the Z85 suspension is higher rated, not sure how much, plus it has air load leveling. "Suspension Package, Standard, increased capacity, Premium SmoothRide with Air leveler 1 - Included and only available with (NHT) HD Trailering Package."
mikebte
Explorer
Dec 14, 2015
When I was single without a worry in the world I would over tow all day. I have, as much as twice the trucks GVW.

Now that I have a family I would get a new Tow Vehicle. You can, and people do make there trucks tow more than GVW every day. Safety is number 1, and if you have an SUV I am sure you have passengers.

Now that being said, I have a 59 chevy I have pulled over 10K LBS. GVW 5K. From California to Oklahoma. Video below.

I installed a good trans cooler, brake controller, wiring, sway control. And I have 3.38 Gears. Pulled the 3.90 So I could go 55MPH.

https://youtu.be/_cNYP2aY19Q

Hard to give advise when I have broken the rules ( I was younger ). But that's my experience. Take it for what its worth.
Knminton
Explorer
Dec 14, 2015
After researching, I have the external transmission cooler (KNP), and HD engine oil cooler, upgraded radiator and fans (KC4), even though I don't have the HDT (K5L). I have confirmed all of these coong components I have are from the K5L HDT package. The only items I don't have from the HDT are the gears and IBC. Not sure why anyone would take all of the cooling options and not take the gears. I couldn't care less about the IBC as I will just add a P3. Thanks for the input.
lbrjet
Explorer
Dec 14, 2015
If you can upgrade the cooling system you should be good to go. That is necessary. Upgrading the gears is the nice to have.
deltabravo
Nomad
Dec 14, 2015
Knminton wrote:
Ok, thanks guys. That solves that one. I assume there is no way to change the gearing without modifying the PCM?

You can, but engine RPMs will be totally different with lower gears, and it will for sure throw off the speedometer, and might cause other anomalies since the engine is at a higher RPM for a given road speed.
Knminton
Explorer
Dec 13, 2015
After looking at my RPO Codes, our Yukon XL has an interesting mix of towing features...maybe they are standard? We have the 3.08's (GU4), Rear locker (G80), heavy duty engine oil cooler (KC4), external tranny cooler (KNP), and HD trailer provisions (Z82), but no Heavy Duty trailer package (K5L). Does anyone know if the only thing I am missing is the 3.42 and IBC options? Or would there be several varieties of the oils and tranny coolers?
APT
Explorer
Dec 13, 2015
The 3.08 gearing isn't that bad, better than the older 4-spds with 4.10 axle.
If GM offered the 3.08 gear with HD trans cooler the tow rating would be around 7500 pounds vs. the 8000 for 3.42. I think if you add that, use tow/haul mode, limit to 4th gear max you'll find 5000-ish pounds dry just fine. All for under $200 instead of losing $10k on a less than 1 year old vehicle.
Knminton
Explorer
Dec 12, 2015
colliehauler wrote:
Knminton wrote:
The Yukon XL is the GMC version of the Suburban. As opposed to the Yukon which is the sister of the Tahoe.
I should of seen you had the XL, my bad.

It's all good. Thanks for all the input guys.