1990 Hammerhead and the 2003 Convention Submarines.

Since I have a few Hammerheads, I decided to customize one of my extras. At present this is about 95% complete. I need to get a set of the front guns, paint them black, and get those in place and when I get a chance get some blue plastic wrap and put that over the yellow canopies to simulate the bluss glass used on the con subs then it will be all set. The plastic is easy to get, but the front guns might take a while to track down since Hammerhead parts aren't too easy to find.

After Cobra Commander learned of the destruction of the G.I. Joe team's mobile command base, the General, by the Black Dragon Organization, he decided that he should have more firepower ready during his first meeting with the Black Dragon's leader as they had proven they were not to be underestimated. In addition to having a unit of HISS II tanks refitted, the Commander commissioned a new deep water vessel. This vessel - a Cobra Hammerhead - was updated with the most modern of technology supplied by various black market profiteers. Due to the rising cost of black market technology only one of these upgraded subs was able to be made before the Commander shifted his economical focus into expanding the powerbase of his empire.

This upgraded Hammerhead was later reportedly stolen by members of the G.I. Joe team. Its current whereabouts are unknown.