If you are running a cruising or highway ratio like 2.92, 3.08 up to 3.55, the EP90 will work fine for you. If you have a 3.73 or deeper R&P, say, 3.90, 4.56, or?, then you will benefit from the EP140 lubes
Most 9” Ford pumpkins normally run whisper-quiet if they are set up properly. If they are not, no amount of lube is going to fix the problem. Pumpkins have specific fluid levels necessary for proper lubrication and cooling. Exceeding those design specs will typically not do anything good for you. If you have sufficiently overfilled the pumpkin, then normal operation will cause the
oil to foam and usually come out of the breather.
If the noise is coming from the ring and pinion, then it is time for a new R&P. If it is coming from a wheel bearing, then it is time for a new wheel bearing. If it is coming from a damaged spline in its corresponding side gear, then it is time for a new axle and, most likely, a new side gear.