Mopar information:
Cudas and Challengers discussion forums. Just joined this one myself, but looks interesting especially for the tech threads.
For parts listings, try Hemmings Motor News under the Chrysler (Mopar) Parts section in each monthly issue. There are also lots of cars listed for sale under the Dodge and Plymouth sections. Pick up a copy at your local newstand or visit their web site.
Mopar Muscle and other magazines have ads for new parts. Mopar Muscle also has lots of excellent 'tech' articles on specific parts of restoration projects.
USENET newsgroups are usually excellent sources of advice (as are the Factory Service Manuals {FSMs -- get reprints from YearOne}). Here's the main newsgroup I used to lurk: alt.hi-po.mopars. It's mainly a few Mopar racers, often flamers, in this group anymore.
Wikipedia's Plymouth Barracuda Info
Special Interest links:
Like rescuing and restoring the ultimate muscle cars? How 'bout doing the same for the ultimate muscle (and teeth) dogs? Adopt a Dobe!
National Doberman Pinscher Rescue Website
Or, better yet, if you are within a long driving distance of Kansas City: