2004 Pontiac Grand Prix front end noise

2004 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic

I have a 2004 Grand Prix with 55,000 miles on it. It started making a noise in the front end on the drivers side. I looked everything over myself but could not find anything loose. I took it to a local repair shop and they could not find anything ether. They where at a loss. I took it to the local GM dealer who said it was a bear bearing which I did not believe because it does not seem to change with speed. So I changed the front wheel bearing myself. (I work on my cars all the time and have a nice shop and tools) I still habve the noise. I have it at all speeds, under power, coasting, brakes on or off. I have it on smooth roads no bumps. It does not get worse on bumps. I do not blieve it is the half shaft in the steering. Makes no difference going straight or turning. I checked all mounts and they seem good. I does seem like a rotating sound but slow and steady which does not change with speed. I checked CV joints and they are good. Do these cars ever have problems with bearings in the transmissions where the axles go in? Please help.