When I remove the torque converter from the flex plate is it critical to mark the location of the tc to the flex plate? I already separated them but was told they should be marked. Thank you.

 

No

 

I have never marked them & have never had a problem.

 

I've heard of marking the flexplate to the crank before, but not the torque convertor

 

On Olds motors, the crank flange bolt pattern is not symmetric, so the flexplate/flywheel only goes on one way. No marking needed.

The flexplate and torque converter are balanced independently, so again, no marking needed.