[LeftCoast32]

The thing that makes the overdrive so nice is:

My speedometer is off by 20% with the current 3.73 gears and 35" tires.

My new axles have 4.56 gears = 20% difference.

The current gearing in 4th (1 to 1) is good for the 283 running down the freeway at 70 mph (lots of power).

With the TKO-600RR the overdrive (0.82) will have me at about the same RPM at 70 mph as it is now.

The TKO-600 with it's overdrive (0.62) may be too tall for the 283 to pull anything in 5th.

**This will allow me to correct the speedometer error if I stay with 35" tires. I have tons of power at 70 mph right now so it should pull the trailer just fine in overdrive on the flats and still have 4th (1 to 1) for the mountains. I can easily change over to the 37" tires once the big block is done.