Hello all,
I am in the process of changing the rear end gears on my 03 3500 from 4.11 to 3.42. Does anyone know what I will need to do to re-calibrate my speedometer? Can a downloader do it, or will I have to change some parts? Will I have to take it to a dealer?
Thanks.

 

probably just a scanner might do it

 

I don't have a scanner, but my dealer is cool and did it for free.

 

I might add if your truck is a 97 or later it will require changing the gears in the tail end of the transmission.