When installing a Th350 or Th400 behind a LS engine while using a dished flexplate from 4l60e transmission you will need this crankshaft flexplate adapter spacer to line up the nose of the torque converter / stall converter with the crankshaft. 
The spacer will center the nose of the converter to the dished flexplate.
For use on LS based engines using a TH350 or TH400 transmission.