The harmonic balancer doubles as the crank pulley. I think a series II like yours requires a balancer pulley puller. You can borrow/rent one from a lot of parts stores. A new balancer is around $100, I think. You will need to jack up the car, remove the passenger front wheel, and fender liner, and crank bolt. You'll find the motor will turn when you try, so you'll need the special flywheel holder tool or jam a screwdriver just right in the flywheel teeth after you remove the plastic flywheel cover on the bottom of the driver side where the block meets the tranny.
But let'* decide if it is your balancer or not. If you grab a serpentine belt can you get the belt to move along its path much? I could have moved mine an inch or so, and it made pullies rotate when I did so. Get a flashlight, can you see cracks in the rubber on the pulley?