My oldsmobile CS is making a very loud rumbling noise loud enough to where it hurts my ears?

My car sounds OK when I start it but as I drive it, there is a very loud low rumbling noise. It's so loud that I can't drive with the window open because it hurts my ears. It's that loud. Is it a muffler problem or a transmission problem. I'm concerned about the cost to fix it. I haven't had the best of luck finding a good and honest mechanic with previous cars. My car is 1993 Oldsmobile CS.|||It could also be either constant velocity joints if front wheel drive or regular universal joint problem with real wheel drive.