FYI I did find a diagram that listed 91611-61014 and it appeared to be right, though the diagram was not very clear. I'm having a hard time finding one that clearly labels that bolt. The dealer in town said 91611-61014 was replaced by 91612-B1014, but I got it and it's definitely wrong (way too large in diameter).
I will probably pick up some machine bolts at a hardware store and see which works. Or I might try other bolts from other stuff under the hood (since I don't think this one is particularly special) and identify it that way.
Andy