are 47re autos weak?

NewMy 01 Cummins made 329,000 kilometres b4 I rebuilt the tranny. The lock up clutch was slipping in the torque converter when pulling. So I then went thru the tranny. I pulled everything in overdrive. Kim

Well... that may have been the problem. Slipping is never good for any transmission. Getting out of lock up and OD when pulling anything is always a good idea.