Strange noice coming from the front when the vehicle is motion

Hi, my first post in this forum. Hopefully someone will help me with my problem. I have LHS 97 with 135 000 km, and a week ago I started hearing a loud sound coming from the front while driving over 40km per hour aprox, I went to the 3 garages, after driving my vehicle and then lifting it they came to a conlusion that the sound coming is from transmission, to be more exact - differential. I don't know much in cars, but they estimated 10 hours of work to get to that part..I hope they're wrong and it can be done cheaper, I suspected a ball joint but after they checked it's not. What other information I can provide so you can help me identify the problem ?
Thanks.

describe the sound that it's making.