Whirring Sound...

[kiwi_bird]

Hello all, I have a 1972 F250 and it has been making this whirring sound. I tried reading into it and most of the other posts have been about the pinion bearings in the rear differential.. all i read online was that if i got under my truck and if the drive shaft moved at all when i shove it around, then that was the indicator of worn out pinion bearings. I did this and nothing under my truck was loose. -also im not sure if that is the only way to check the bearings, it was just the most common way that everyone recommended. I tried moving tugging and pulling on everything under there and everything felt good. But, this whirring sound persists and i was wondering what else could cause this sound? It only happens when I am in motion, as I accelerate, the whirring sound speeds up and as i decelerate, it does accordingly. If you guys could help me out, i would appreciate it!

[BobbyFord]

Maybe a front wheel bearing or rear axle bearing. I would pull the wheels and inspect/spin each hub.

[tnlprt]

Did you have the rear end off the ground and the transmission in neutral when you checked the drive shaft and rear end

[kiwi_bird]

I'll check the back hubs next.

But, no i didnt do any of that when i checked the drive shaft.. that the proper way of checking im guessing..

[fordman]

Throwout bearing yoke shield on pinion shaft? Im guessing