Tystevens

Hello all. I am in the process of shopping for a "new" Suburban 1500, and have a couple questions for you experts out there. First, a brief introduction. We are a growing family of [soon to be] 6, and are looking to upgrade our current '05 Suburban 1500 to a newer model. We use the 'Burb as my wife's daily driver, to take long road trips, and to tow a 27' travel trailer that weighs between 5500 and 6000#, depending on the trip. Our current 'Burb has 4.10 gears, and tows the trailer adequately. My father and my father-in-law both have 2011 or newer Silverado 1500 pickups, and I have been quite impressed by the 6 spd transmission's performance. Seems like just the ticket. As our '05 has passed the 125k mile mark and is getting a little long in the tooth, we are about ready to upgrade.

I'm looking at '09-12 Suburbans on the used market. I looked at 3 trucks today. All had the RPO code for 3.08 gears. While shopping today, I did not know the K5L RPO code (which, now, I obviously do). However, I did look under the hood, and each of the 3.08 'Burbs had an apparent transmission cooler in front of the radiator, and had a very small, 2-coil width item on the passenger side of the radiator, which I guess may be an engine oil cooler? Now, it was my belief that the "HD towing equipment," which I believed mostly consisted of the additional cooling elements, was not available on 3.08 trucks, and yet there it was, or appeared to be.

So, my question is, do the 3.08 trucks sometimes come equipped with the same cooling equipment as the 3.42 trucks? Or would the K5L package incorporate more robust cooling?

Also, a couple caviats. I understand completely the issues with GVWR, CGVWR, axle ratings and all of that. Also, I understand the mechanics of the actual gearing differences very well. In reality, my question isn't whether I "should" get the 3.08 or 3.42, but rather pertains to the auxiliary cooling equipment that is found on these trucks in their various states of optioning and packaging.

Honestly, if the 3.08's have similar cooling capabilities, it may be a better choice for us than the 3.42. The 3.08 would return better freeway mileage when not towing - we take a few long trips out to the West Coast each year, so improved freeway mileage would be great (our 4.10 geared 'Burb doesn't do very well on the freeway, usually around 17 mpg). We do tow a couple times a month in the summer (and almost always in the mountains, to boot), but most of our trips are weekend trips under 250 miles these days, and I am fine towing down a gear to compensate for the higher gears (looking at the 6 spd's ratios, 4th gear X 3.08 ratio looks like an improvement over what I've been getting from my current '05 truck, anyway). So I'm not really worried about the performance difference in gearing. But I don't want to risk overheating and so on, obviously, if the 3.08 trucks aren't going to have what they need to keep the transmission cool.

The other issue is that in my shopping efforts, it appears that 3.42 trucks are going to be fairly hard to find, especially '10 and '11s, so if I can get a 3.08 truck that will work out, I'm gonna have many more options on the market.

Thanks in advance!

73shark

The HD tow pkg was an option that I believe included the two coolers.

fishing nut

With the 3:08 gearing you would be over the trucks towing capabilites with your trailer. If I remember correctly with that gearing the Burban is rated to tow 5600lbs. I am not sure if you test drove a burban with 3:08 gearing, but the truck I test drove would downshift going uo small inclines. I do not think you would be happy, so hunt out a truck with 3:42 gearing. I searched for 4 months until I found the Burban I wanted. Settled on a 3/4 ton with the 6.0L V8 and 3:73 gearing.

Tystevens

Thanks for the info. I actually finally found a truck equipped with the K5L package, so I know what I am looking for now. What I thought might be a very large transmission cooler is actually the AC radiator, I believe. The K5L truck I found has a smaller 2 or 3 loop transmission cooler and an oil cooler which are visible thru the grille -- pretty obvious now I know what I'm looking for.

Man, I am a little frustrated with GM right now. I've looked at 20 or so 'Burb/YXLs over the last 3 days, and all but 1 have 3.08 gears and lack the K5L equipment. A 5000# tow rating for a Suburban just doesn't seem right. Maybe the LS/SLE trucks are more likely to be built for work -- I've only looked at loaded LT/SLTs thus far, as heated leather seats are a required option in my wife's book. Between the gearing and the single speed transfer case (no low range??? Really, GM???), I'm feeling a little disconnected from what I thought Suburban's customer base was. I actually looked at a few Expedition EL's (gasp!), which all come w/ 3.73 gears and a low range t-case, and which appear more likely to have the HD trailering equipment as well based on the few I've looked at.

The 2-spd t-case and 3.42 gears were the only options for '09 trucks, so that might be where I end up. But they don't seem much more likely to have the K5L, at least based on the few I've looked at (most have been '10 or newer).

The one properly equipped Suburban I found was an '10 LT w/ Z71 package. It was perfectly equipped inside and out, but a little higher mileage than I had planned on. It was also pretty hammered -- lots of dings and gouges, and a cracked rear bumper. To be fair, I saw it the day it came off the truck, and they promised it would be sparkling for me once it goes through the shop, gets a new bumper and all of that. So that might be my answer, we'll see ...

Tystevens

Yeah, w/ 3.08's, the rating is 5k lbs. 3.42 and no K5L only nets a 5400# rating.

I've driven a few w/ 3.08's. To tell the truth, they didn't seem too bad, and I really like the low final drive in 6th gear -- I can see why they get such good mileage on the freeway. But the 3.42 truck did feel peppier, that is for sure.

I was initially thinking 2500 as well. But they are very rare on the used market, we "need" a fully equipped one, and I don't want to drop $60k on a new rig. After driving my dad's '12 Sierra, and reviewing the charts comparing the 6 spd's ratios to my current 4 spd 4.10 geared Suburban, I've come to the conclusion that a properly equipped 1500 will be an acceptable compromise. The final drive ratios for the 3.08 actually look better (or at least more useful for towing) than my 4.10 4 spd, to tell the truth, and a 3.42 looks like it will work a lot better. My dad's report, coming from a 2000 Suburban, is that the '12 tows much better without that huge gap between 2nd, 3rd, and 4th gear.

In total, we probably tow the travel trailer less than 2000 miles a year, and other than that, the truck is my wife's daily driver and is our road trip vehicle -- a 2500 would be less than optimal for those duties, and I don't want to pay gas for 15 mpg for the 90% of the time we're not towing. Plus, there is a fair chance we'll move to a motorhome in the next few years, which would leave me with nothing to tow but a utility trailer and the Scout's trailer from time to time. So I don't want to go all-in on the ideal tow rig, which will be less than ideal for the rest of our use.

fishing nut

It is definitly frustrating. I was considereing the 1500 as well, but could not find one with 4:42 gearing and the HD towing package. Have you tried using Auto Trader.com You can put in all your options and it will find the vehicle you are looking for.I have now used the site to find the Surban and an ATV I was looking for. As far as buying new I could never imagine dropping 60,000 on a vehicle.

Tystevens

Yeah, I hear ya. I've been using Autotrader. The problem is, at least on most used vehicles, they don't get very specific on options like that -- probably because the dealers are oblivious to them. When I go in an type "3.42" for example, the one used Suburban I know has the option does not come up, because whoever placed the ad didn't include the information.

fishing nut

Man, I feelt like I have been there just recently. I even stopped at a GMC dealership as I was driving buy and saw a Surburban. I asked the salesman about the rearend. His comment was all we have are 3:42 rearends on the lot. When I asked him to check. Guess what all the Burbans had 3:08s. It will be a challenge, but I am sure you will find it.

Tystevens

Thanks for the advice Fishing Nut.

Fortunately, I found one equipped just the way I wanted. 2010 4x4 LT Z71 Suburban with the 3.42 gears, HD (K5L) cooling options. Silver w/ black leather, captains chairs, pretty much everything but a sunroof as far as I can tell. Dealership put on brand new tires (Firestone Destination LE -- not what I would have picked, but I think they'll do). A few more miles than I wanted - it has 71k miles (I was planning on 30-50K), but it is very clean, and hey, not bad to save some $$ and come in under budget, right?

Just based on seat feel and the gear ratio charts I've seen, I can tell that this is going to tow a lot better than my '05 did. Just 4 months 'till camping season ...

Thanks again for all the advice.

fishing nut

Stevens glad to hear you found the Burban you were looking for. Post some pics when you get a chance.