I didn't read every word in every post in this thread, so if someone else mentioned these clubs, I apologize for the duplication.
Mid Maryland Ford Club (based in Frederick)
National Capitol Region Mustang Club (MCA affiliate)
Northern Virginia Mustang Club (Rents Mason Dixon Dragway a couple Saturdays a year for club racing).
All have web pages, but I can't locate the URLs at this moment. They will all come up if you use a search engine and look for Ford, Mustang, & car clubs.
Don, '91 LX - Original owner