'83 460 Econoline motorhome. Drivers side second to last bolt missing from exhaust . How long are those bolts? I can get a probe to go 1 3/4 in. past the manifold flange. Are the bolts longer than that? Has it broken or backed out? Can't see any others missing.
Please, please tell me it just backed out.
Can I buy only one?

 

I replaced my exhaust manifold bolts with stainless when I re-powered my truck in 2008.
If I recall I used 1 1/2" long NC bolts, so that depth/length seems right. (not sure if a van manifold is a different casting)
The thread size is 3/8-16

You need not purchase a OEM bolt, there's nothing that special about them.
An old school autoparts store should have a set of orange Dorman drawers with all kinds of studs and bolts available.
The really trick exhaust hardware is bronze or copper plated so they don't corrode.

 

Jim, Thanks for the reply.

This is in a van and fortunately with the dog house cover off is easily reached. Only the one bolt is missing. the other appears ok. If there was no gasket, will I be able to just put in a new bolt and draw it down and close up the leak. I fear that is wishful thinking, but you gotta try.. Perhaps I should work the remaining bolt out and then draw them both up.

I don't want to have to pull the engine for this one bolt.

After thought....There is a metal spark plug heat shield tucked behind the ear/flange where the bolt is missing. I am assuming there is a relief in the manifold mating surface for that shield.