I have a friend that swears he gets 19 mpg pulling a load of 9500lbs with his 7.3 4X4, he took it in with over 200,000 miles. Said they put a economy chip and did a diaognostic check at a dealer. Is this possible

 

Only if his calculations are coming from an overhead console. Others may chime in here, but that kind of mileage is nearly impossible with a load on. And the only way to get an accurate calculation is the old fashioned way, the over-head consoles are very optimistic especially if they are chipped.

Mike