Take it from someone who has experienced it first hand. I know this is a Expedition forum, but before I bought my Expy, I had an Explorer WITHOUT the trailer package, but did have a 4.6L V8 engine. So the Max rated tow capacity was 3,500 lbs. I probably was exceeding this nearly every time I used my trailer. I was probably towing close to 5,000lbs. While the V8 had no problem with acceleration, my Explorer had a 3.53 rears, and no Tranny cooler, I think the Explorer with HD tow package had 3.73 rears. Well lesson learned, within 2 years after I started using a trailer semi regularly, I had to rebuild the rear diff once and replace the rear wheel bearings 3 times. And now the transmission frequently overheats whether I'm towing or not. I opted not to get the HD Tow when I bought it new, because I lived in the city and thought I would never need it, but then life happened. I met my future wife, got married and moved to the country, where I started towing a trailer hauling gravel, dirt, mulch, and sometimes my tractor. This is why when the motor finally blew, last summer(unrelated to towing) I bought the Expy I now have and made Damn sure it had the HD tow package on it. So take it from someone who has been there. If you even think, you might do some towing in the future, do yourself a favor, get the HD Tow