I've had an exhaust leak that stops after the engine warms up. 4.0. I finally noticed that I am missing a bolt that holds the exhaust header on - the back one towards the rear. I have no idea what size it is???? Anyone know? Thanks.

 

Are you talking about the very end of the cylinder head? If so, if I am correct, that is a stud. Not sure what size though.

 

There are 2 studs that attach to the exhaust manifold only sometimes instead of the nut coming off the stud unscrews from the head. The rest are all 15mm bolts. The studs are located at the front and rear of the head in the bottom. For the bolts I would take one out and bring it to an Ace hardware or something like that to get a replacement.