Here is what I know:
1. Mopar Alley (Been around a long long time. All Mopars, mostly classic muscles)
2. Mid Peninsular Muscle Car Club (All muscle cars not just Mopar, But Stu Harmon (president) drives a Roadrunner and lots of Mopars in the club.)
3. NorCal Challengers (my club, mostly new Challengers only but some members have the classic as well. You do need to drive a Challenger to join)
4. CenCalLX, this is a big club, mostly newer Mopars (Magnum, Chargers, Challengers and 300's)