I picked up this watch recently. It's a 8306-9030 from 1966. I found it interesting where the patina settled in.... it kinda highlights just the "Seikomatic-R Diashock 30 jewels" script just below the hands. The case has some significant pitting from corrosion where the case back screws down and the movement seems to have escape the water intrusion and it runs great! Anybody know what the "R" in Seikomatic-R means. I'd be curious to know. I'd also be curious to see any other patina wonders. The crystal on this model is beefing and it takes the same as the 6105 divers.