hey, i'm brand new to the site and im on here for this very reason. at about 40 mph and up there is a slight grinding noise or metal rubbing along with a floorboard vibration coming from the front end. i don't know anything about cars, but i came across a thread recently that said it could be the u-joints. so, i took it to the shop and they recommended only changing the one that looked warn. the noise lessened but its still there. would it be worth it to go ahead and replace all of them or could the noise be something else? its more pronounced when i let off the gas but i think that may just be because the accelerating sound drowns it out because i can still feel a slight vibration in the floorboards. any help at all would be greatly appreciated.