I agree with stretch. You prolly have taller tires than in the SD so you'll have an effectivly taller final drive. I'd start with around the 307 gear. your truck will have more frontal area so a much taller gear would probably be a bit much to push the boxy ford through the air.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.