It's a 2010 XLT, 2 WD with the HD tow option. I helped my buddy pick up his flooring order, total weight with passengers was 1820 pounds, most over the rear axel. The truck sagged about 2-3 inches in the rear. It drove fine at 70 MPH highway speeds for 20 miles. The tires are always correctly inflated. It has 121,*** on the clock, I am the second owner and I am reasonably sure the struts/coils have never been replaced. It rides fine when daily driving with just me in it. I don't tow anything with it. So is the 2-3 inch drop reasonable for that amount of weight, and should I replace the struts (all 4) because of the age/mileage?