Quote:
Originally Posted by SAR STX
whoa whoa whoa so if the speedometer is off the odometer will be off as well? no wonder my mileage plummeted with the 31's!
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Yes. A mechanical odometer is driven by the same cable as the speedometer. The speedometer is driven by how fast the cable spins, the odometer counts how many times it spins -- typically 1000 rotations equals 1 mile. If you don't calibrate the speedometer when changing tire size or rear end ratios, your odometer is going to be inaccurate too. I don't know how many times I've seen people post in the Mustang forums about they changed gears, and they get exactly the same MPGs as before. Then find out they didn't change the speedometer gear, so the odometer is showing more miles than actually driven.
Quote:
Originally Posted by cdawall
Mustang rear ends wont work in your truck at all. Size wise they are two small roughly the length of two short side shafts.
Your 2.3 will likely get worse gas mileage dropping the gear ratio to far down. Your best bet on MPG's is driving habits.
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I assume the OP is referring to the rear end internals, and not the housing. And yes, dropping a gear ratio too low can have a negative affect on mileage, especially city mileage. 3.27 is probably as low as you'd want to go, and you'd only gain about 1.5 MPG over 3.73s, and maybe 2 MPG over 4.10s.