I need to remove the front head off my 3.3L Grand with 167k miles. Is it necessary to remove both heads or I can I take off the front only? Also, what's the best method for breaking the head loose as I'm assuming it's going to be tough to get out.

 

You can only take off one but I'd do both if you are in that deep. The head bolts shouldn't be too terribly hard to break loose, last one I did I just used a regular ratchet but a breaker bar would be easier.