I used this spray corrosion stop product from Home Depot ..(my photo attached)
I got the idea that this area (the space between the inner and outer roof sheet metal) might be a problem area deserving of attention from board member "bcutt" who did his roof sheet metal restoration and took the trouble to try and help the rest of us by posting photos of his work (please see attached photos of his from this forum) back in December 2011
Actually I really think bcutt should have gotten some kind of maximum award or medal for his total heroic effort on the part of devotion to these trucks... he did an amazing job - On one of the most technically difficult sheet metal areas - lots of compound curves and close tolerances..Class AAA work!
Here is a link to what he shared:
http://67-72chevytrucks.com/vboard/s...d.php?t=496154