I replacedt the timing belt on '96 300zx but couldn't get the crank to rotate the desired 120 degrees in either direction (spark plugs removed). Alignment looks good. What is the chance that it will go out of alignment.

(QUOTE)I replacedt the timing belt on '96 300zx but couldn't get the crank to rotate the desired 120 degrees in either direction (spark plugs removed)

Did the belt snap while the car was in motion? If it did you should know that this is an "Interference Engine".

(Quote)Alignment looks good.

As you stated you can't rotate the engine 120 degress in either direction Soooooo, please tell me alignmnt of what looks good? I love to learn new things.

(QUOTE) What is the chance that it will go out of alignment.

Very high

This is an interference engine (meaning that the piston will hit the valves if the timing belt isn't installed correctly). also the piston hits the valve if the timing belts breaks. Did you timing belt break and that's the reason you're replacing it?
If so, then you most likely have bent valves which are keeping the engine from rotating.
If not, you've just got the timing (belt) off a little. In that case just start over and pay close attention to the belt tensioner mechanism (make sure it doesn't leak oil and that it keeps the belt tight).