That valve was current inventory at Hamilton as of 6/23/2010. They turn a LOT of inventory in that aisle. Will check again next time I am in. According to the rep they are also bonded with a glue to the threads but he was kind of clueless so I was a little weary of this statement..

I have a box of Marelon in my barn that I will check also. Perhaps only certain sizes are pinned?

EDIT: Just went to the barn and pulled out TWO 3/4" tri-flange Marelon seacocks and neither have the pin but BOTH are totally glued to the threads and even in the vice would not break free. I suspect I could have forced it but felt I was up against a failure pressure. Both were removed because they were getting quite stiff but interestingly enough they now rotate somewhat OK after sitting in a dry barn for about three+ years?

These smaller 3/4" ones have no pins. They came out of a boat built in the late 90's and are Forespar not the older RC Marine valves which I also have a few of kicking around. They appear to be glued tight though. Perhaps will destroy one tonight to see what's holding it on there.