Great photos, thank you. That's what we have, the same brackets as in your photo. Because the "hold down clamps" (or whatever part they have for holding down the hood which holds the tank)are missing, all we have is a photo of another '29 D that uses sort of a bent iron clamp that bolts to the support bracket. As the bolt is tightened, the clamp pivots and pulls the hood down tight. But the ones in the photo we have bolt to the support bracket inwards about 2" or so, not on the outside like in your photo.
Can you post a picture of those clamps (or whatever system is used to anchor the hood downwards)? I suspect that somehow we might have either the wrong tank or the wrong brackets (and are missing the clamp parts).