th400 problems...have question

[67cst]

last night i was going up the highway and all the sudden i hear this loud whining noise, i pulled over right away and as soon as i stop moving it goes away, i checked all the fluid levels in the truck and they were fine, when i pulled back onto the highway the noise was gone, then again on the way home it did it again, i is pretty loud, this time i put it in neutral and after a couple of seconds it was gone, put it back in gear and drove straight home, so it did it 2 times...what could this be? do i need a new torque converter possibly? i dont know much about these transmissions, im still learning all this fun stuff, could someone help me figure out this problem? thanks in advance

DEREK