I think the original question was about 68's, I'm not sure....
On 1969's, the baffle pan most definitely mounts OUTSIDE the valence, not tucked inside the valence, so the u-bolts mount to the valence, not the baffle pan.
As for the u-bolts, they can be found at a good hardware store, in black oxide, and the body bolts as well (I believe Hillman is the manufacturer, not Dorman). I think most Ace Hardware stores in our area carry them in the nuts and bolts section, in the automotive 'pull out' drawers.
