Holding the crank from turning
 

How to hold the crank from turning in 1996 impala SS while the engine is in the car to tighten the bolts of the crank pulley and the center bolt of crank. I need to tighten these bolts. Need help.

I ran a chain through one of the holes in the pulley then to the chassis.

How do you hang the chain to the chassis?

OK, I think I figured it out, you hang the chain to the sway bar with a lock. That's cool.

pry bar through the inspection plate on the flywheel.
you need a 2nd set of hands / helper, though, to do
that.

Get one of the tools that's used to hold/turn a flywheel. It has a couple of "hooks" that grab the teeth of the flywheel, and you can either turn the flywheel, to access the bolts, or hold the flywheel, to tighten the bolts....

long extension through the pulley towards the engine.

I did the chain way and it worked flawlessly.

Thanks.