Caseback
6309 casebacks re-stamped or swapped to read 6306
Critical
What to inspect
The premium the JDM reference carries makes the caseback the obvious target, and on a Turtle the caseback is a separate, freely interchangeable part. Never accept the caseback number alone: confirm it against the hacking test and the jewel count on the movement. A caseback saying 6306 over a non-hacking 17-jewel movement is a misrepresented watch.