TCI GM speedometer gears fit most popular transmissions like the Powerglide, TH350, TH400, 2004R, 700R4 and others. Choose from many gear options.

The following formula will work for any GM, Ford or Chrysler vehicle and is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line.

# Drive Teeth x Axle Ratio x Tire Rev. per Mile 1001

= # Driven Teeth

Use the following formula to calculate the Tire Rev. per Mile for the above formula.

Tire Rev. per Mile =

20168 Tire Diameter (inches)