would this be the torque converter?

[burgess]

So after a loud clunk im sure my tranny is toast. i was told by a few people its the torque converter. I can still start the car up fine,rev it in park like nothing happened but when i put it in gear it will only rev up to 1700 rpms and the car doesnt move, its like its still in park. Also when the cars in park it does not hold the car. unfortunately for me i have no working e-brake. But i just wanted to verify that the problem is because of the torque converter or something else in the transmission. And what could have caused this to happen.