If you had it rebuilt twice and the noise hasn't changed, it's time to look elsewhere......
If you have a whine coming out of a differential what I've run into is improperly set pinion depth. And in the two case I've personally encountered, the noise was different under acceleration versus coast. If loading does not change the noise, I'm with slantzilla, time to look elsewhere.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
