Chevrolet Repair: whining in rear end, 89 Chevy 1500 4x4, chevy 1500, driveline

Question
I have a whining,almost sounds like a race on a bearing spinning while I am driving my truck. If I give it gas a put a load on it, it will quite until I hit the cruising speed or let up on on the gas.
Let me know what ya think.
Thanks

Answer
Hi Bart,
Sounds like you are sure in the right area.
Jack a rear wheel up to take the load off the driveline, and put it in neutral, so you can see if there is excess play in the pinion.
I'd even remove the rear cover, and look for unwanted wear on the teeth.

Van