Bill,
Changing ratios, tires sizes, rims size..will affect your tranny shift points. speedometer. i t cost me $100.00 at a frod dealer to re-program the computer. I believe it can be re-calibrated one more time in case i change sizes again or the ratio.
Check this www site out:
https://www.ford-trucks.com/tfts/calc.htm
good luck,
al