The older axle, which was installed just about 2 years ago, was purchsed from NAPA and was supposedly the best on the market (which is not saying much). And yes Subaru Nut, it only happens on acceleration. You could be right about it being the inner joint. I know the noise is coming from the driver side which has the older axle but I'm almost certain it isn't coming from the outer joint. That's why I was wondering if it was coming from the tranny.