I would not think so unless the torque convertor was bad before you decided to change your transmission.I would also decide by how old the convertor is.the wear and tear over time.in other words was the torque convertor part of the problem why your transmission needed replaced.in other words either inspect it or have someone inspect it.one article I just read says to either rebuild the torque convertor or replace it at the same time you rebuild or replace the transmission.so I guess the big question is do you want to risk leaving the old one in and putting in the new transmission to find out you have to take out the transmission again to replace the old convertor.you could see how much a transmission shop would charge to test the old convertor.I just checked and a factory rebuilt replacement can go from 255-400 dollars depending on the convertor.(tpi convertors).so I guess the big question is it your money or your time that is more valuable to you.