Recently purchased Lariat F250. Had 4Wheel Parts add leveling kit and 37" tires on 20" wheels.

My speedometer is showing 7/8 mph slower than what I am really driving.

Does anyone have a any DFW contacts who can recalibrate my speedometer to read correct MPH?

I have contacted two Ford dealers in my area and they claim they cannot do such.

I have looked online, and have found a device that I can purchase and hook up for reprograming. But I don't trust my workmanship on that.

Looking for a 3rd party who has experience and equipment to perform recalibration.

Thanks in advance.