t case speedo gear ?

[ford1386]

I have a 94 ranger with a zf tranny, np205 t case, 3.55 rear gears, and running 35'' tires and I'm wondering how many gear teeth on the speed sensor can I change without changing gear in t case. I'm currently running a 17 tooth gear and I'm gonna put the gps in my truck to see how far off the speedometer is and then use the chart in the tech library and see what gear I need to make it right

 

[ford1386]

Bump

 

[ford1386]

Called patc and the guy said I can change the driven gear as much as I want without changing the drive gear in the t case. That doesn't make any sense to me but in gonna check my speedo against my gps and see how far off it is