A couple of details.

OIF bikes' handlebars are rubber mounted. There are two large "metalastic" bushes. The 'P' bolts go through the bushes and are locked by a washer and nut, but in between those there are supposed to be FOUR more bits. I know, it seems like a lot and I guess it is a remnant of the old construction philosophy that carried over into the "modern" era of the 70s.
Anyway, these are the four extra bits, and they do make a difference to the handlebars, mostly to cut vibration.

I also remembered an old trick that I saw some people use a few years ago: a piece of fuel pipe stashed into the handlebars, out of sight when you ride, but always there should you need it.