I can't seem to find this piece ? I played the game all the way through on the light side, and have all the other pieces...
Nevermind...
"You get the Vocalizer on Peragus from the first HK-50, the Control Cluster from the HK-50 trio on top of the Telos Academy, the Processor from the droid parts merchants on Nar Shadaar and Onderon, and the Chassis from the HK-50 trio in Vogga the Hutt's droid warehouse.
So yeah, fastest way to get HK-47 up and running is to finish Nar Shadaar right after Telos. "