I've got friends with newer chev PU getting about the same mileage. Also a contractor friend getting about the same with his Powerstroke Ford Diesel 3/4 ton 4X4. New american trucks are awsome. HOWEVER... I'm anal about vehicles. Used to be in the auto industry watching people make strange decisions with their buying/driving habits. I want to stay under 20K with this vehicle. The locking diff is aftermarket and I'll install it myself and yes it's about $400.00. Toyotas isn't a true locker as most manufacturers aren't. Most are limited slip. Bill