Hey, you all are right, no Allison trans. I had to look for myself, I’ve been saying it for years and no one else has ever corrected me(even when buying filters and fluids; I even talked to the dealer parts department) Well now what, I still love the truck and have never had any problems beyond a cracked exhaust manifold. I have 128,000ml and well over half of those towing something. My first TT(heavy old Terry, as heavy as my 26bhxl but 4ft shorter) I didn’t use the trailers brakes for a year(illegal) and I didn’t get a weight distribution hitch for 2-3yrs(have air ride). I’ve been all over these western states: Canada-NewMexico and over to South Dakota . I have never gone around a mountain, just over them , and the only time I can remember being in first gear was coming into Jackson Hole from that Teton Pass(10% grade). I have never put my foot all the way down, I don’t like to work the engine over 75%. 95% of grades I can do at 50-60mph(always passing bigrigs) up but I do like to do 45-55mph downhill riding the trany(oh crap, its not an Allison). At the end of hill I might let her run up to 70+mph, just to help with gas mileage. On the tough long incline grades this puts me in second gear between 3200 and 3700rpm, she likes to run there. My trany and engine temp gauges have never gotten to the red(close only once in Az)and I’m always running my AC(tougher on engine) but I do change my fluids and filters way more often than recommended. At least 50% more, I first changed: difs, transfer and trans at 10,000ml (what I called break-in) and then every 30,000ish after that(oil at 500ml, 2000ml and then 3000 since). Now gas mileage I try not to talk about so lets make it quick and get it over with: 15mpg standard and 11-9mpg towing (I always have the largest Yakima box and many times a kayak on top: I have to blame something on the poor mpg.)
I love my ride and I have been towing something since I was 16, parking and backing down boat ramps since I was maybe 14. My first vehicle was a ‘76 ¾ ton Dodge and the worst was a ‘94 F250, she could tow great but when she wasn’t loaded she’ld bounced your teeth out(wife wore a sports bra).I have had under powered and, no I cant say “over powered”, can never have enough power. I have yet to make the jump to a diesel but some day.
I am sure there are many other better(relative) tow vehicles out there but I love my 2004 Yukon XL Denali, most comfortable ride I have ever been in and tows great for me(never had the tail wag the dog, always goes where I tell her to).
Big Guy(me), two kids a wife and a dog with all their needed stuff/garbage and there is a ton of room left over; going to keep her a while longer, hopefully 2 more years.
I gab too much,
Use your gauges often(a must for towing: tach, trans temp, engine temp, oil pressure and throw in a fuel gauge just to scare you), find your drive train’s power band and stay in it on grades but don't over do it always save a little, maintain your equipment like you tow, go slow-ish and enjoy the view/ride