I looked at mine to day while I checked the Auto Trans Fluid and I was surprised to find that while I have the Nut on the Engine part of that Gold Colored Bracket I do not have a bolt; it is missing just as the OP's picture.

I have had My Manifolds off once and I have no recollection of a missing Bolt, having trouble getting a Bolt in or losing a Bolt???

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84 300D, 82 Volvo 244Gl Diesel