i wonder if some used a long extended van and made modifications like putting in a smaller motor ford (or whatever brand ) 302 or 351 and also changed the rear axle gears for better milage if it would be worth it or is their some long full size extended ford or chevy or dodge vans with smaller motors already in them around that size ? does someone have a link that would show different engine, etc. sizes that are available for full size extended vans ?? a web page showing axle ratio's etc. for the best gas mileage would be good .