The 85 has a 2.88 gear ratio so will give a 7% or so taller final drive, so it will give a bit better fuel economy and quieter engine on the highway at the trade off of slightly slower acceleration.

To me the improvement is slight enough I prolly would not change it for that reason, only if there was aproblem with the 307 ratio rear end

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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.