By bolt #12, please refer to the drawing below. When I got my truck, bolt #12 was missing. “Not to worry”, I was told; it only holds the exhaust pipe bracket. My exhaust system was home made by the PO so no bracket was there. Well, when I finally installed the stock exhaust system this past summer, I ran a bolt up thru there to fasten the bracket. I did not put a bushing (#5), nut (#3 lower) or rubber damper (#10) in there as shown. What a difference in engine vibration! Before I put this bolt in, my engine would shake when pulling out or especially when backing up. Now, smooth as glass. However, if you look at the drawing, there is a nut, #3 (lower one), and a rubber bushing (#10) that makes bolt #12 a floating stud with its base attached to the frame plate. I did not do that as an all thread bolt was not available at the time. (The drawing doesn’t show the exhaust bracket under nut #3 upper). I believe they did it this way so the engine vibrations would not put stress on the first exhaust pipe or the manifold bolts. The first exhaust pipe rocks with the engine, so no stress on the pipe or manifold. Also, this bolt is necessary to dampen vibrations on the engine/transmission mounts. The pipe hangers would take care of any remaining variations further down the exhaust chain.
Questions;
What damage or problems could be created buy just running a bolt up there like I did?
Since the exhaust bracket is not shown, is there in reality another nut on bolt #12 to fasten the exhaust bracket? (Nut, bracket, nut)