1960s 1964 Cadillac exhaust manifold bolts question

[Cadillac Jack 82]

So my latest purchase has a missing bolt towards the rear passenger side exhaust manifold thats causing her to tick under acceleration.  I was told it was missing when the seller bought it.  Are the bolts for the manifold the same size/length?  I see Caddy Daddy has a set for sale and I'd like to fix it next weekend with my neighbor.

[Clewisiii]

Talk to David king. He had exhaust manifold bolt sets that were remade. For 61 the bolts are all the same except for the front passenger side. It is about 3/4 inch shorter. I had to cut it down myself
Though the block is flipped the manifolds are the same on LH, only bracket difference on RH.

[Jason Edge]

The 12 factory exhaust manifold to cylinder head bolts has a 9/16" hex head, thread is 7/16x14. The two left driver side rear bolts are 1 1/2" long & others are 2 1/4" long.  The bolt shank size (7/16"x14) is a common size and you can find bolts with this thread at hardware stores but that 9/16" hex head is smaller than the standard 5/8" hex head found on most 9/16" bolts.  I have plenty of the longer original 2 1/4" long bolts and like the one missing on your passenger side.

I sell that bolt in very good condition for $3 each, which drops to $2.25 with 25% Chapter discount.  If interested email me at jasonedge64@outlook.com. If keeping the exact bolt head appearance is not important, you can find the 7/16"-14, 2 1/4" long bolts at places like www.boltdepot.com. You just want to make sure you get the Grade 5 or Grade 8 (preferred), hardened bolt. I am showing the bolt depot price of $1.39. Click Here to check it out. You may also be able to find the bolt at the local hardware and home improvement stores. Again, if you want the exact original bolt I have it.

[Poncholover]

In my experience, it is usually only the back end of the bolt that is missing, the rest is safely nestled down in the hole. Hope this is not the case.
Cheers!