speedo

[nomad1500]

my speedometer 15 mph slower then gps say 55 and speedometer reads 40 350th mated to np203 transfer, 3.07 rear end gears, 31"tires, transfer gears are red 7 teeth and steel driven 20 teeth.

 

[Snoots]

Most 350's with a 203 had 3.73 rear gears. (You probably have a 3.08, not a 3.07)

Let me know if this works for ya:

file:///C:/Users/Roger/Documents/Automotive/Tranny/Speedometer%20Driven%20Gear%20Calculator.mht

or this:

Speedometer Gear Calculator

or this:

Speedometer Drive Gear Calculator

Quickly calculate your speedometer drive gear size for your transmission with this easy to use calculator

moveras.com

 

[Matt69olds]

TCI Auto Speedometer Gear Calculator - TCI® Auto

Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. This 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!

www.tciauto.com

Or this

 

[Camar068]

was kinda scared to read this one with the title......but anyway lol

should be an easy fix once you figure out what gear you need.