And the part # also. 3462871 crosses to Dorman 555-008, which is a 9/16" plug. All I had to do was look through my Larry Shepard small block book to find it. Or do a slightly more in-depth google search. As RRR said, guessing got me in the mess I have now, my fault 100%. The fractured pieces poppped out with little effort, not a lot of meat missing. At this point I'm thinking I'll knock down the rough spots on the saddle side, have the hole upsized a tad, push in a short sleeve,and have it dressed down to the block's cap mating surface. My friend has a marine diesel shop, I can get the spot magnafluxed for free. The crank bore in this block was never touched, I have a spare set of ARP main bolts, I'll just put them in and have it honed after the sleeve's installed. I know I freaked out yesterday morning, but now it doesn't seem so bad. It's only money.