For over a year now my 98 Isuzu rodeo has been making a loud roaring noise only when i am accelerating above about 20MPH. My vehicle has over 200,000 miles on it. I've taken it to a couple different places and they dont know what it is. It's a very obvious roaring/whining noise. Like i said, only occurs when i am accelerating. Then when i take my foot off the gas it goes away. Any ideas? Its really annoying and I'm a little scared it may cause some serious trouble eventually.

 

I would guess the backlash has too much play, take it to a transmission shop, you don't want to mess with that...I've seen ring and pinions explode if not adjust right within specs. Hopefully you haven't been putting on too many miles since this started. If soo expect about 6 bills to repair...
Good luck and stop driving her if you can.