Yes, there was a 28? page supplement for the 67 barracuda. Here's a link to some scanned copies of the Service Manual Supplement. I purchased a 67 manual with the supplement already included. Hope this helps.
I have an original 67 Plymouth shop manual and there isn't anything in there about Barracudas. Is there a supplement to the factory manual that covers Barracudas? Just wondering, it would be handy to have for body-related issues.