What's the absolute maximum range of your Duster?
I did! I had a 64 Ford 1 ton stretched with a car hauling bed. A lot of drag racers were using the Cheby Big Dooleys. But I saw a black Dodge dual wheel pickup that I wanted. Adventurer SE loaded up 400 2-barrel automatic. Traded my Ford for a car hauling trailer plus cash. Fuel mileage was terrible like about 11-12 mpg unloaded at best. Then I was told that the 400 2-barrel was the worst. And for some reason the automatic would upshift way too early keeping the engine bogged down. I played around with some different springs added to the kick down rod to make the trans think I was pressing the gas harder. It wasn't too difficult to get it to act like it was supposed to. No pics of my Dodge though.
