How do i correct speedo for 4.10's???

[97RedGT]

I have a set of new ford racing 4.10's ready to be installed. I have a used sct x2 tuner than i need to get tuned but am told that i will not be able to use that because of the year car i have. I guess anything older than 98 has the options of a speedo gear, or a speedocalibrater, not even sure about this one. I have read that a speedo gear will not 100% recalculate for the gears... I am not even sure what tooth is needed for 4.10's. Does anyone know what tooth is needed for 4.10's in my car and what mph it will be off... And does anyone know about using a speedcalibrator for a 97? What should i do?

 

[Jrgunn5150]

Use a Dallas Mustang SpeedCal

 

[gt96stang]

Use a Dallas Mustang SpeedCal

for sure.. that's what i have.. and i'm happy I went with that choice instead of the cheapo speedo gear.