Hi JSS, Sorry for the late reply and thank you for your information.
No. They are not Halyard Lead Blocks. Its weird. I've attached some pictures to show you what I'm talking about. I think it is compensation for a design flaw. There is a deck cover that goes over halyards and sheets from the cockpit to the mast. Underneath that deck cover is what the boat manual deck hardware list calls a halyard roller and a halyard roller bracket. The purpose for these two parts is to hold the halyards and sheets down so they don't rip up that deck cover piece when putting loads on the halyards and sheets. The halyard roller bracket is made up of a stainless steel bar that has six 1 inch delrin rods that the bar slips into and 3 brackets. Each bracket has two holes that get secured to the deck with SS machine type screws. Screwed in and not secured with a washer or nut. That's 6 more holes in the top of the boat.
What happened to me is, over the years, there was so much pressure put on the halyard bracket, the brackets lifted off the deck and when it rained or a wave washed over the deck, water came through the ceiling and recessed lights in the salon shorting some out.
So, my thoughts are to secure the halyard roller brackets better by adding SS washer and SS nylon nut to each screw on the bracket and sealing with silicone or caulk. Or, cut the deck cover back to just after the deflector blocks and glass over the 6 bracket holes and call it a day. Please let me know any thoughts you may have. Thank you again.