I have a 2007 Suburban 1/2 ton, it has 4 wheel drive and the factory towing package. It also has 3:73 gears and the air ride suspension. I assumed it had the factory air to fluid trans cooler. I talked to hoffkm and he said I don't think so. So off with my trusty flashlight, and low and behold I did not have one. hoffkm gave me this link.
GM Parts Direct: Your direct source for Genuine GM Parts
For the factory cooler, I printed it out and went to my local dealer and they did not match the price, but they came close when you figured the shipping.
I had it installed today, it was a balmy day in southwestern Ohio, 24 degrees and after going down the highway for 20 miles, my trans temp was 136 without the cooler, coming back, 3 hours later, we were up to 26 degrees, and the trans temp was 109 with the cooler. My truck has 40,000 miles on it, we changed out the rear end fluid, used Mobil 1 75-90 and I going to do the transfer case, front diff. The transfer case takes a special fluid, it's called Auto-Trak 11, only from GM the part number for this is 12378508. The front diff. does not have synthetic in it, so I'm going to switch both. They are easy, they have both drain and fill plugs. I'm not trying to throw money away, just preventive maintenance.
Hope I have not bored everyone to tears, just some info I thought might be helpful.