I have a new set up in a truck that is using a 09 corvette e38 and t42 from an 08 truck. The trans is an 02' 4l60E out of a Firebird. I am having issues with the trans. I know the trans works fine, it only has 20,000 miles on it and it drove fine in car. In the scanner the vehicle speed is not working but trans output shaft rpm is. It is difficult to get the shift points set when you don't have vehicle speed logged to compare it to. Also it does not like to down shift when you push the pedal down. It will only down shift when the truck slows down enough to reach a speed for it to down shift on its own. I would be glad to post a tune but mainly looking for why the speedo is not working.