Here I answer some of the questions on the P1811/harsh shift codes on these transmissions. If you drop the pan and find alot of clutch material or metal it may be time for a rebuild.
Parts:
PCS 2003+ 24225825
Shift Solenoids x2: Delphi SL10020
Filter (reuse your old pan gasket):Wix 58837
Transgo Shift Kit: 4T65E Transgo Shift Kit
Spacer plate for 2007+ (yours may be different, have the dealer search for it by vin#): 24243102
Side Cover Gasket: Fel-Pro TOS18723