Hi guys, I know this is an old thread, but this may help anyone removing these type driveshaft bolts. There are special sockets made just for these, and they're super nice. Impact type, two lengths, one is about 4 inches long, one is about 8 inches long. 1/2 inch drive, with a slender shank down to the 12mm 12pt socket driven end. These are actual driveshaft bolt sockets. Some other manufacturers use them as well, and you may find them in 10, 12, and 14mm, depending on what you're working on. They're designed to use with a 1/2 drive impact wrench, no swivel adapters or extensions needed. These take the fight right out of those bolts, use one once and you'll love it. I have several of them, and I got mine from Mac Tools and Snap On Tools. I was a dealership tech for many years, and I bought the majority of my tools from those two as well as Matco. I'm not positive whether you can get these from other sources, but you can just do a Google search for driveshaft bolt sockets, and they'll pop right up. I hope this helps!