I have a hellacious exhaust leak on my 96 F150, with the 300 straight 6. I took it to my shop, and they said the leak is coming from the air injection rail, which they say is loose and broken. I've looked at the rail, and it seems ok to me, I'm not sure where its broken, but they say its about $660, parts and labor to fix it. They say its about a 6.5 hour job. Anybody have any experience working on the air injection rail, or ever had this problem?

 

It's a common problem, and takes less than two hours to replace, for a rookie. Anyone that's done it before could do it in an hour. The rail itself will set you back about $120, though.