torque converter
 

how do you test to check if you whipped out the torque converter in a 47re or is it possible to just replace the torque converter and valve body without replacing the whole transmission?

Yes you can replace both the tc and valve body without doing anything else to the tranny. Although it is best to replace the flex plate when replacing the tc. What are the symptoms that lead you to believe the tc is bad?

transmission slip and hunting for gears