Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
Engine out and onto an engine stand is the easiest and less stressful way.
Why do you need to replace crankshaft?
No.
Engine out of vehicle, removal of engine supplements.
Engine on engine stand upside down - sump facing up.
Have you got a service manual? If not, go purchase one before you even attempt to remove the engine.
Make sure to loosen the harmonic balancer bolt before removing the engine too, otherwise you'll have alot trouble later on.
well theoratically you could remove it from under the car but you're making things very difficult.....
much easier and less stressful as stated above to do it out of the car on a stand, that way you can have all the components lined up on a bench and not risk mixing b/end caps up and main journal caps, not to mention when fighting gravity and lying on your back getting things to stay in place like bearing shells, moving the conrods and pistons up/down to put back on the crank, still have to raise the engine block to clear the k-frame, trans would have to be removed etc etc etc.......
What's wrong with the engine you have currently?