04 dodge 1500 rearend gear change. How do i correct the speedometer?

I'm changing the 3.92 gear to a 3.55 on my 2004 dodge 1500 4.7 liter a/t I need to know how to correct the speedometer?04 dodge 1500 rearend gear change. How do i correct the speedometer?
The speed sensor is connected to the ECM. You need to take it to the dealer to have it reprogrammed to the right gear ratio.04 dodge 1500 rearend gear change. How do i correct the speedometer?
a dealer will have to do it ,they can re-calibrate it for the gear your changing to,unfortunately they are the only ones that can do it,so that cuts out the small shops,good luck.