Jim, I'm a diesel fanatic but if you are already getting over 20 mpg w/ a gas truck it would be a negligible benefit to go through all that hassle. I am also skeptical about the ~35 mpg unless it was a very light truck that doesn't carry much.
Do you just carry light-weight surveying equipment? I wish that Toyota and the others would market a light-duty diesel truck here like they do in the ROW. I'm a 3/4 ton guy because with the diesel it gets better mileage than a gas F-150. Plus a lot more capacity+ towing. If it wasn't for the diesel I would not even consider driving a 3/4 truck around. If a Toyota had enough room, I'd drive the 4 cylinder 4x4.
