Had a guy that come into our shop that has a Detroit with DDEC 3 ECM on his truck. He wanted his speed set up to 75 MPH. I hooked up the computer and found his truck had had the ECM changed. He has a direct transmission in it with 3.08 ratio rears. The computer was set up for overdrive ratios, wrong size tires etc..
I set the tire rev/mile to 498 (11R22.5)
The top gear ratio to 1
and his axle ratio to 3.08
I am not sure about the VSS Teeth It is set at 16. (does anyone know what this should be?) It is a RT14710B Eaton Transmission
Anyway after making these changes he says he can't go faster than 72. I have the speed limit turned off. But if I did check it on it says max speed is 70. The VSS type is set to Tail and the signal is magnetic.