Reply to "half shaft question"

Unfortunately, it IS important. If the crosses in the u-joints are not matched to each other, severe vibrations will occur. This is called a 'phasing error' and is serious. Basically, the two crosses in both u-joints must be aligned to each other in a given half-shaft. The further away from perfect, the worse the vibration will be. Depending on which halfshafts you have, there may or may not be indicators. Old joints will need to be pressed out and new ones pressed in with care.