Glenn is dead nuts on the money, beef the tranny......

The other thing about using an overdrive tranny and hot rodding the motor is that you have to make concessions on the cam and the static compression ratio. If the crank is going to turn at 1700-1900 rpm's at cruise in 4th gear, then the cam will have to be up into its operating range at that point in order to make good gas mileage. I mean, that's the intention in the first place, to make good fuel mileage with an overdrive transmission, right ?????

So then, you can't use a big hot rod cam that, for instance, makes power from 2500 to 6000 and expect any kind of gas mileage, because for gas mileage, the cam will need to be efficient at the rpm's the crank is turning in 4th gear (1700-1900). A cam that begins making power at 1000 rpm's (with an operating range of 1000 to 4500) is the type of cam that you will want to use to insure fuel mileage. Otherwise, if you use a hot rod cam, then you will not need an overdrive transmission and could make the truck work with a TH350 or TH400. The cam you will want will probably not exceed 204 degrees duration @0.050" tappet lift and will want a 9.00:1 static compression ratio. Any higher static compression ratio will want more cam, which will not work with your overdrive transmission.

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