Whining/whistle noise- possibly pinion bearing?

Okay so ever since I bought my XJ (it was completely stock), it has made a whirl/winding down/whistle noise when coming to a stop. It's like a whistle that goes from a high to low pitch. Recently, it has started to do it under heavy acceleration as well. When I put the pedal to the floor, it starts to do it at a certain speed and gets louder with the RPM's. It is definitely coming from the front axle. Finally, another symptom which I'm not sure is related is whenever I come to a stop, I get a bad vibration from the front end right as I'm about to stop. Based on what I have read, I am thinking it's a bad pinion bearing. Any thoughts? Thank you.

Vacuum leak is a high pitch whistle?
Check your front driveshaft for looseness or rust coming out of the U-joints. The same for the U-joints in the front steering knuckles. could also be front bearing hubs. lots to inspect up front.

Ron

I pulled my front drive shaft and it still did it. I will check the knuckle u joints/hubs. Thank you.