hehe, I use an impact wrench. that makes it REAL easy. If you don't have that you need to use a "poor mans impact wrench". That means from under the car put your ratchet/breaker bar on the bolt and while holding it near the extension, hit it with a big hammer in the direction that makes it turn counter-clockwise. This will overcome the engine turning from the inersia of the wrench. If you are using good tools, pad the wrench with a shop rag so you don't bang it up. I used to use a soft faced dead blow hammer and that works well, but any BFH will work. Remember, it's the speed that does the work here.
After that to remove the ballancer you will need a special puller availible at parts stores or you can rent one from a rental place.
Hal
Love hard, drive fast, wear your seat belt.
PS, thats's my 'bird...... My Mustang is too ugly to take pictures of yet........*G*.
http://www.teleport.com/~cosa/bird2.jpg