What's the size and thread of the passenger top rear exhaust manifold bolt? I found the source of the small exhaust tick. The bolt is gone...

 

I replaced the left manifold on my 88 301 and bought the bolts from NAPA in a kit from the help section, all the stores carry the kits. You need to use a tap or thread chaser with oil in the old threads and make sure the bolt is not broken off down inside the head.
I used a loaner thread chaser kit from Orileys. With that you can tell what size thread and get a single bolt.

This may not be correct but from my 88 manual, for a 7..5 engine they are 3/8-16. and the torque for a 5.0 is 18 to24 ftlb..
maybe I just haven't learned to use my CD manual but i could not find the 5.0 bolt size anywhere...

When I bought the manifold bolt kit the bolts seemed like they were a bit tight but they are working fine a year and 6k miles later. I think mine were 3/8-16 also.. Your van is a bit newer though so it could be metric

 

On the 'net I've also found 3/8-16 as well. Thanks for your reply. As for it being broken, that's a real possibility. Probably at some point the PO broke one off and left it that way. I've certainly seen it before.