I'm with skippy on this. These engines have good power for climbing hills with the stock gearing. If you put gears in that will raise engine rpm you will really ruin the fuel economy. the engine is an air pump. If you raise the cruising rpm 20% you will raise the fuel burned commensurately....I mean close to 20%, so if you go from the stock 288 gears to 346 gears that is increasing the highway rpm by about 15%. So if you are getting 25 highway mpg now that will drop to about 20.

Its nothing I would ever do.

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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.