something doesn't sound right. I frequently towed almost 6000lbs (boat) with my 01 suburban with 3.73s without issues. sure, it would drop a gear in the hills, but no crazy ...

something doesn't sound right. I frequently towed almost 6000lbs (boat) with my 01 suburban with 3.73s without issues. sure, it would drop a gear in the hills, but no crazy back and forth shifting. are you 100% sure on your towed weight? does the engine feel strong otherwise? have you done a compression check?

Yes the towing weight is accurate. I have not done a compression check because the engine does feel strong. Even completely empty if I'm using cruise control it starts to go up the slightest Hill it will downshift two gears in order to maintain speed. I just seems so unnecessary to downshift 2 gears and have the engine at such high RPMs just to maintain speed. And I live in Florida so our Hills are nothing like some of the hills that you guys are used to LOL

One thing to consider is the transmission fluid. What's the mileage on the truck? And how often was the fluid changed?

What fluid are you using? It might be worth going to a full synthetic if you're towing regularly.

Hope my experiences are helpful, my 04 has the 4.8 and 3.42 rear, 140K miles. Pulling more weight though, a 4500 pound camper with about 700 pounds in the truck not including tongue weight. Did put a shift kit in it for towing. I pull at 60-65 and yes it drops a gear on florida overpasses. In Pennsylvania on hills it is typically running about 4000 rpm on long hills. I lower the cruise a bit in those situations. I have used the trailer towing switch, all it seems to do is shift out of OD earlier and back into it later. No effect on trans or engine temps. My measure of how hard it is working is MPG. Full load on the flats is just under 12. On a hillier drive just over 10. Empty with one person in the truck I am getting 17 on the highway.

Recently pulled a car trailer with a prius loaded, got around 14 at 60-65. Much easier pull, trailers are like big parachutes!

Bought this vintage truck because it doesn't have the AFM crap. Aside from one rocker it is rust free and I intend to keep it for a long time, as long as rust doesn't kill it. The motor and trans can be replaced for less than the cost of upgrading to a year without issues. If the motor goes, it will be replaced with a 5.3 , right now I am mentally debating a different rear axle ratio but overall am very happy with the truck as a tow vehicle.

I would suggest some mpg tests to see how hard the motor is really working. But with that weight at that speed you should not have a problem unless there is already a problem. Hope this helps.

The truck has 208 thousand miles. I I was told that the transmission was rebuilt at some point but I have no idea. I got the truck with 192000 miles and the first thing I did was a transmission service change the fluid in the transfer case and both differentials Etc. There are some things that I really love about this truck but then some things that I don't. It's the basic version that had roll up Windows a rubber floor mat no power door locks Etc. I put one of those kits on it to convert it to power windows and door locks and the door locks work great. The power windows work okay but more times than not one of them doesn't want to go back up. From the research I've done it would be very difficult to put true OEM power windows in this truck.
So I'm kind of at a crossroad. I know the truck is going to need some money put into it sooner than later and I'm not sure if I want to put it into this truck or try to get something a little newer. But finding out about the issues with the truck so I can afford definitely is a deterrent.
Pretty much all I ever use my truck for is Towing. At the weight I have listed. I may possibly go up to around 3,500 lb eventually however.

I'm not sure if I should look into a 2500 or an F250. I don't have to have the extended cab I can use a standard cab with no issues at all. Hopefully that will get me a better truck for less money. But I'm not so sure I want to get into the modular motor of the F250. Thanks again for all the help guys

I think I would keep the 06 in your case. No need for 2500 with that towing weight, and the 09 1500 would be about the same as the 06 but with nicer interior. You would have to go down to the 4.8 V8 to avoid AFM thus negating the extra power. A tune would get the power back to where you had it before with a stock 5.3. But i'm pretty sure the 4.8 V8s only come with the 4speed trans anyway. Then if you get the 09 with 5.3 and 6speed you need to rebuild the top of the engine to make it reliable.

Have you done any engine tune ups to it? Plugs, wires, clean the mass air flow. Maybe one of the sensors is causing a false high engine load reading and causing to downshift more. Something seems odd with dropping two gears like that for a small hill. Mine did not do that when I towed a little N*** sedan a while back

Yes sir I did. About 16,000 Miles when I did all the other maintenance I did plugs wires clean the mass airflow sensor Etc. Any idea what sensor could be causing something like that?

Usually the MAF is the one causing issues, its very sensitive, but would have to look at live data to know for sure.

Another thing i didn't see mentioned, Do you have stock sized tires or larger?

I agree, if your truck isn't a rust bucket keep it. I went from a 2000 to a 2010 I don't regret the move I do like the 2010 and at 160k miles still going strong with a tune and the AFM disabled. Just think the 2000 was a simpler easier to work on truck. If mine wasn't falling apart from rust I would still be driving it.

OH, the 2000 had 270,000 miles on the 5.3 and it was still going without burning any oil to speak of. It was also a WT with no creature comforts. The 2010 has electric windows, door locks and remote start. Main reasons I like it better than the 2000..

275/55/20 is the tire size i have. Not sure what the stock size is. I know if mine are larger than stock it will make the 3.42 gear even worse.
Can the AFM be tuned out or do you have to tear into the engine to disable? I have no rust on my truck but do have some dents and what not and paint in so so. Mine does go through a good quart of oil between changes. Which is one of the reasons of contemplating of selling for whatever i can get. My truck still runs great and is very reliable but i know eventually it will need a rebuild of engine and trans at some point. Just dont know if i want to put that kind of money into this particular truck.