I have an '04 4L automatic, extended cab, 4X4 Offroad. The offroad package included 4X4, 4.10 rearend, and transmission cooler.
I pulled my 18' 3500# Jayco TT from central Pa as far as Joshua Tree NP.
My dog and I boondocked for 110 days and logged 7,900 miles.
My best milage not towing and strictly highway has been 17-18. Around town, 14+, towing 12.5 consistently.
On windy days driving I-10 across TX, I did wish it were heavier. I towed with OD off and maintained 60mph at about 2700 rpm.
It runs steady and smooth, didn't use a drop of oil since I've owned it. I bought it with 130K, and it currently has151K.
I love this truck and won't replace it until it needs major repairs... or I win the lottery. It's payed for and does what I need.
I've never named a vehicle, but this one is named Little Big Red, (and I love talking about him, ?).