Rear end noise question

I have a 1992 Majestic. Getting it back on the road after sitting for 13+ years. It has a noise in the rear end starting about 30mph but goes away at about 70MPH. Sounds like a tire whine but I just put new tires on it. Any ideas?
Thanks, Jay

Have you checked the wheels for possible bad bearings?

Check the fluid level in the diff - also, try this - when going about 40mph, with no traffic around, put the transmission in neutral and listen for the noise - if no noise, then not the rear end - wait till come to stop, then put back in drive to continue home - transmission noise will sound like rear end noise while driving down the road mine did this when the transmission clutches were going out.