2003 Pontiac Grand Am grinding noises from engine or front

Would you describe the noise as a roar or hum. Does the pitch change if very to the left or right?

Does the noise follow the rpm of the wheels or engine?

Will the noise happen if the car is in park and the hood is open while it idles?

Rules out a wheel bearing.

This is starting to sound like an internal problem in the transmission. I have heard of various causes of noises that stem from the tranny. I'd say start by checking the condition of the tranny fluid, but thats is brutal with out a lift as there is no dipstick.

But have you seen any red fluid leakage at all? That may be a sign, but not necessarily. IT may be worth getting the codes checked to see if any transmission related ones are stored in it. This may not be a di-it-yourself kind of thing. A scanner will probably have to be hooked up and have it driven so a technician can monitor the datastream to see what is happening.

I'm really surprised there is no check engine light as this has to be affecting emissions. Based on the rpms and noise I would lean towards a speed sensor or more precisely the problem with the gear meshing of the speed sensor, broken teeth etc.

Codes need to be read before doing anything as I see it. I expect a transmission code to be in there of some sort at the least.

I don't know your area and the quality of the dealerships. Dealerships are only another shop under the manufacturer name brand. They are only as good as the individual techs and the ethics they follow. Some are great some should be run outa business. Independents are no different. I find there are a cut of independents that are above most, but finding them isn't always easy.