Before changing the Manual Shift Shaft, Detent Lever, and Position Switch Assembly on an Allison Automatic Transmission, first take off the control valve assembly from the transmission. Take out the detent lever/IMS retaining bolt with a T27 TORX(r) bit and get rid of it because threads are treated with patch lock material. Make sure you do not damage the transmission case surface or twist the pin while taking out the spherical pin. Put a protective plate on the pin before you take it out. Put the manual shift shaft through the detent lever/IMS assembly and the manual shift shaft seal, then rotate the detent lever/IMS assembly so you can remove the park pawl apply assembly. When installing, put the new detent lever/IMS assembly into the transmission case, line up the park pawl apply assembly with the slot, and reinstall the manual shift shaft . Make sure the manual shift shaft is all the way in, install Reattach the control valve assembly last, then use a scan tool to do FastLearn and make sure the TCM has the correct adaptive values for the new parts.