Sounds like one of the bearings in the diff to me, although the directionality would point to the ring and pinion, however that would normally grow in sound level over time and would generally not start all of a sudden unless the diff was run out of oil.

I'm going to try to get the car in the air this weekend and see if the diffy has oil. I'm positive I pour enough in (I poured until it came out of the fill plug) and unless I have a mysterious leak I don't see it going anyplace. I took it for a fairly length drive today (30 miles or so) and the sound only seems to occur upon acceleration from a stop. Say up to about 5 mph. After that the sound disappears and doesn't return until I again come to stand still and have to accelerate again.

I've done some research online and for what I'm seeing it could possibly be a u-joint. I know that these don't "squeak" but some people have said that it is possible.

I just don't see the diffy just randomly starting to squeak. Wouldn't it also make some kind of noise at higher speeds. (or all speeds at that). I'm not doubting your guys knowledge but could a diffy go bad in 300 miles? I mean it wasn't making any sounds when I bought the car in August. I've only driven maybe a 1k or less with the car. And only 300 with the new Redline 75W90 I poured in to the rear end.

Sorry about the length but your advise is very useful

Jan

Well a "squeak" doesn't sound like a typical description for a noise made by the rear end, but a "roar" as you put it does. It's hard to know for sure without hearing the noise ourselves, but it's certainly possible that this is due to one or more bad u-joints. Since that's already been diagnosed as a problem perhaps you should just tackle this and see if the noise goes away.