Yes my dad has mentioned a mileage drop. I'd say it has stock-ish tires, no lift. Pretty close to a stock truck, its a one owner with under 100k. I'm not sure on the gears. 4 speed manual trans.
So it sounds like mid to upper teens would be a good estimation, which is much better than I would have guessed, 15 would be great in my opinion.
Here's pics.