I bought a 460/C6 combo a few weeks back, and I've been kinda tinkering around on it. I noticed it had some of the rubber freeze plug inserts in the side on the block. I pulled one of them out, poked around in the water jacket, found 2 steel freeze plugs lying inside the hole. The steel plugs weren't rusted or damaged and obviously didn't pop out, so i don't really know why the rubber ones were put in. There are only 6 freeze plugs on a 460 block (not counting the cam plug or any internal ones), to date I have removed 8 steel plugs from the inside the block, 4 rubber plugs, and 2 of the factory steel ones are still installed. So, thats 14 freeze plugs and only 6 holes, lol. Bizzarre. Any ideas?