help with harmonic balancer

I am trying to remove/replace my harmonic balancer in my 2002 grand prix se. I need to find a way to stop the crankshaft from turning, and suggestions? I am relatively new to really working on my car, usually just did basics like oil, fluids, etc. any help appreciated!

3.8 or 3.1?

if its a 3.8 there is a plastic inspection plate on the bottom of the motor between the tranny and the back of the motor.

two 10 MM bolts hold it in place.

then put some vice grips on there and break out the breaker bar or an impact wrench.

15/16ths.

unfortunately its the 3.1

then unfortunately i haven't the faintest clue.

Look for an inspection plate in the same region.

Impact.