I was trying to diagnose my own tranny problem and with what is posted on the net I have not found anything that logically seems like my problem with our tranny. It was fine one day and then just out of the blue stopped shifting from 2nd to 3rd it still shifts great from 1st to 2nd and does reverse great. Not sure why, does anyone have any thoughts that might diagnose this problem or make any logical sence. we have checked the Detent cable, Vacuum Modulator, and fluid on my THM 350 chevy transmission and all were fine. Could you please offer any suggestions on how to fix this problem? Any help is deeply appreciated. Thank you, Craig and Missy craigandmissy@q.com