I don't have the original bolt, so I can't tell if it was metric or SAE. The wedge I have is just a random one I grabbed from a bin at the Reno Bike Project. It is threaded 5/16" x 22TPI, which is British Fine thread.

Yes, that's EXACTLY what I need- thanks! I'll grab one of those to install later on. For now, my larger bolt retrofit will have to do, as my tall woman is hitting the road to Burning Man in a few hours. I'll be making no changes to the stem itself, so installing the correct bolt later on will present no difficulty.

Darron