constant whine

252,000 miles, inspected driveshaft, original center support bearing had large movement but no cracks or rips, so I replaced the center support bearing (Spicer, had all the same markings as the Spicer OEM part) and added a new greaseable Spicer universal joint. Also inspected the two end universal joints and they were tight and smooth. I plan on changing those out soon. All fluids, brake, power steering, rear end, transmission have been replaced (transmission stutter fix, and fluid was 1.5 quarts low, between the two, 12,000miles stutter free since, have cycled 3+ quarts five times to flush tanny). Radiator flush hasn't been done, up next...Truck has no leaks, a few normal weeps...

Anyway, I went through this 'whine' crap on my first gen, turned out it was the rear end. Thanks to a member here I was able to purchase a cherry replacement, installed it and moved on.

Since the whine is constant accelerating or decelerating I am a bit baffled. Over the years I have had rear ends go bad, and all of them had different pitches for accel or decel. All of them were heavily abused street racing or at the dragstrip, the exception being my previously mentioned first gen.

Maybe a wheel bearing? (front/rear) I am second owner, the truck has been babied, previous owner always took it to the dealer, I have full records, not abused. I drained the rear end, the magnet on the drain bolt had a small amount of metal debris, minor, very fine, I would consider normal for mileage. Replaced fluids with 3.2 quarts full syn 75/90....

Whine can be faintly heard from 5MPH up to about 55MPH, then fades at higher freeway speeds. It has remained constant for the last three or four weeks.

BTW, the new center support bearing makes life smooth. And having the zerk is a bonus...

Opinions encouraged.