Recently for the past couple months, my car has been making a subtle howling noise at cruising speeds. It is most obvious around 2000RPM on the highway if you are giving enough gas to maintain speed. If you let off the gas, it ALMOST disappears but if you concentrate you can still hear it.

The transmission only has about 3,000 miles on it and other than a couple kinks to be worked out, isn't giving me any catastrophic problems.

I'm leaning towards to rearend. It is a stock rearend (I do know that this either the 2nd or 3rd rearend that has been in this car, but other than the fact that it is a GM 10 bolt know nothing of It's history), and I do have nitto drag radials. I do like to get froggy sometimes from a roll 20MPH or above, but have NEVER done any WOT launches since getting the Nitto's. Waiting on a rearend rebuild to do that.

Just trying to see what you guys think and what I can expect.

 

It's your rear end! Needs rebuilding/replacing!!! It could last a long time or break tomorrow??? LOL

 

Check the rearend fluid level. If it's low & dark brown, change it out.
Full & dark change it.
Use the recommended Gear oil weight & type.
To me it sounds like the rear end is howling.
If that doesn,t work, may be time for ring&pinion change.
Just a thought....
Good luck