Here's instructions and pictures on how to repair a cowl vent.

http://mustangbarn.com/Cowl_Vent_Repair.htm

 

Great information. Although I have been chastised by some of our members for too many stickies , I am going to make this a stickie. This is one of the most common problems we old mustangers have, and this is some super information in how to deal with it. Thank you for your post.