Gear ratio change

[Matt]

I have a customer with a 2000 Silverado. He is wanting a lower gear ratio 3.21 to 3.73 I think. What is the procedure for flashing the PCM to accept new ratio?

[Ruston11]

Ratio Change

I don't think it works this way with GM. I think a super chips or one of those type devices is needed in this application.