I've got an 02 2wd single cab longbed 4.2l 3:55 gearing and I had the bed so loaded with even heavy cement bird bath and cement dolphin and base. Took a forklift to put in truck. It big and heavy plus red landscape bricks at least 20 of and a lot of other stuff.
Was moving from Texas back to ohio so bed was full of stuff with just nuff room to close the tonneau. Anyway had it loaded where it was squatting real good. Like I was driving up a hill all the time. Wish I would of went over a scale to weigh it
BUT To the point. All the way from Texas to ohio it did great and was getting close to 22 mpg at 70mph on xway. Didn't give me a bit of trouble and no huff and puff. A bit sluggish goin up a grade. But nothing where I had to turn on flashers. Lol.
All in all I would tow a car and trailer behind mine any day. In fact I did in Texas had a car trailer with a 99 ranger loaded up and pulled it bout 200 miles and no prob. It's no 5.4 I know so I know there was power loss and such but a 4.2 can pull a load. Just wouldn't do it every day LOL.
Here the only pic I have with the fully loaded down bed getting ready to leave Texas and head back home to ohio.