Hard shift accures during 2nd to 3rd when shifter is in overdrive automatic mode. It dosen't accure when shifted manualy or in manual mode. It makes a loud bang in the diff probly due to torque being transfered down the driveshaft. What could make a pressure spike in the tranny other than the computer? The trans has been serviced but to no avail. Could it be in the valvebody? Someones help would be appreciated.