i have a howl that seems to be getting worse. it seemed to start when i changed the springs. it used to only be slow speeds, and now it happens at any speed. i dont think it is the bearing but i am going to check it in the morning. any other ideas? tks

Be sure to check the U-joints carefully. By changing the springs, you have effectively changed the angle of the half shafts and that could be where all the noise is coming from.

what would i be looking for? and if i found something i would get new ones?

I also have been nursing a cyclic howl from the backend on my 1971 240Z. I believed it to be the differential but when I pulled it apart last week found a very rough noise from the rear wheel identified after disconnecting the axle shaft. Source was the outer bearing on the stub axle. Rough universals in the driveshaft or axle shafts may also generate a howl or clunk.