bought 2008 dodge dakota big horn rwd about a month ago already replace the front wheel bearings but still hearing the same noise when i turn (grinding sound) and feel a rumble about 40mph any idea what the next step might be

 

Get the tires balanced....maybe check the brakes, dust shield, etc.

 

- 4wd? - CV axles (clicking or thumping noise on turning). Also, do not use 4wd or turn while in geartrain is in 4wd on dry ground with good traction. Doing so binds the drivetrain, causing alot of grinding noise and potential damage, Stuff will snap!. Only use 4wd when it is slippery. ex: Ice, mud, loose gravel.
- overdue Differential oil change, limited slip (noise on turning, shudder on take off or light turns)
- 40 mph rumble could be: tire balance, sticking brake shoe or caliper, worn driveline universal joint(s), worn shocks.