[dfwright]

From the looks of the other one, there's a lock washer integrated with it? If you have a Fastenal nearby, it might be worth taking the other one out and taking down to the Fastenal to see if they have what you need.

I will state the disclaimer that the ones around here have disappointed me a time or two on what I thought should be a commonly available bolt.

You might also want to consider heading over to the parts board, and find DLTRUCK1973's hardware thread and ask if he has one. I've bought a bunch of bolts and other miscellaneous hardware from Tom.