We tow with a 00 Burb 4x4, 5.3..27 feel, 5800 pounds. It does fine. It took me a couple of trips to figure the thing out. I added Sumo SuperSprings to the rear. I keep mine out of overdrive and run around 65 MPH. When I'm pulling a steep mountain I don't let it lug, I'll pull it down to 2nd gear and let it rev (55MPH+-). It pulls my trailer just fine. I use towhaul most of the time but, in stop and go traffic I take it out of towhaul. I doesn't need the higher RPM shift point to be comfortable in city traffic. The 4l60e isn't an issue, that I have noticed. I do a drain and fill on mine at every oil change to keep fresh Dex6 in it. And, when I'm towing I take it easy. Never had any issues with my transmission, at least not yet. I bought a cooler and pulled the grill off to install it. Then I saw the factory installed extra cooler and didn't install the aftermarket cooler. It's still in the box in my garage. I haven't decided if I'll install it. Frankly, I don't think I need it. I pulled my transmission pan a few months ago and replaced the filter. I then ground down the stock drain plug and welded an 11/16 nut to it, cause that's the fist one I grabbed out of the spare hardware bin. So, now the plug comes off easy so, I can do a drain and fill in a couple of minutes.
There's been exhaustive discussion on this forum about transmission coolers. You can look it up. If you have the factory tow package and keep your transmission serviced...and don't try to kill it while towing it should be fine. If I were pulling up mountains a lot I'd add the cooler. Most of our trips are beach trips. We went to the mountains once last year and I just pull it down in second so there's no hunting for gears. When I get home from a trip like that I pull the drain plug and replace 4.5 quarts + -. People will trash the Suburbans, Yukons but, I love mine.
My wife does dog shows so, we need a vehicle that has climate control in a large area and will tow an RV. And, I like the 4x4. I was looking for a Ford when I found the burb. It was such a good deal I bought it against my better judgement. It has turned out to be a great vehicle.
