I can't believe I don't have the big end diameter written down. I resized a set of 263 con rods a few years ago, and found a specification somewhere. Right now, I feel I must have taken it from the "Specifications" chart in the list above, but I don't have a rod available to confirm it. If you planning on upgrading a set of babbit rods, you will have to figure a way to cut the locating groove in the rods too.