I installed a used AOD into my 66 Mustang with a 302. The condition of the transmission is unknown other that the seller saying it was "good". My issue is this: the transmission works but I have to rev the engine to about 3000 rpm before it starts to move. So my question: is the transmission slipping or do I have a high stall torque converter and how to I tell the difference? Any assistance would be appreciated

 

Converter stall speed has nothing to do with normal transmission operation. Does setting the shift lever to other positions result in the same thing?