Seiko 6309 Tuna mod - Discussion thread
There has been some interest when I posted pics of the mod (6309-7040 dial, 3rd party insert) 
Or 6309-7290 style dial w/ original insert (watch on the left)

Thus I have decided to do a short writeout (I believe CEO also has the same mod).
Inspired by :
http://www.thewatchsite.com/index.php?topic=5469.0"http://img13.imageshack.us/img13/5210/dsc7255w.jpg" alt="" loading="lazy">



Cheers and good luck ,